The control/pushrod separates..... Then what?

[fiveboy]

Maybe I am unique (I know I am not) but as I fly, and when I am on the ground.... I am in fact obsessed with, thinking about how I fly and what to do.

Yes, I look continually for landing spots (have to here). I rehearse what direction to approach for prevailing wind and what switches to make sure are off in case I have a hard landing, etc etc etc.

But am I alone in thinking about, what would I do if some part of my control rod system were to detach rendering my stick useless?

I think my trim spring would offer some stability, but in fact it would be essentially a runaway gyro....

ok guys..... now what do we do?

[JonVos]

I've always been concerned about that as well. I preflight my machine completely before every flight, paying close attention to the control rods and cables, but still, Murphy's Law applies and anything bad that can happen eventually will. I've always been a fan of having a backup control system like some of the old gyro's I've seen only in pictures with a motorcycle type handlebar arrangement that extends down from the rotor head with a solid metal bar. The controls are reversed, but hey, it'll get ya on the ground.
I've also considered running a set of lightweight backup cables parallel to the control rods. In the event of a control rod failure I'm sure the stick would be sloppy, but perhaps still controllable enough to safely return to Planet Earth in one piece.

[Jazzenjohn]

I read a post here where Birdy would fly by grabbing the control rods over his shoulders. I've tried that and found I could fly it better by grabbing the rods below and behind my seat. It might save me if the problem was further up the chain. My next gyro may have a small rigid bar attached to the control head like Jon mentioned.

[Chuck Roberg]

There was another thread that addressed this same scenario. Of course I can't find that particular thread right now but it had a picture of one solution.

As I recall Birdy had another solution he uses.

[Alan_Cheatham]

There is an article by someone in an old PRA issue that dealt with this, his solution was to tie two pull strings to the control bar and with some practice could fly by manipulating the strings. Very light weight too.
.

[Aviomania]

:spy: Or.... use the system i am building now.... :D

[Chuck Roberg]

Found the other thread. What you want is toward the end past post 100.

http://www.rotaryforum.com/forum/showthread.php?t=19919

[Jazzenjohn]

Check out this thread too, especially posts 31 and 36 from Ron A and Birdy.

http://www.rotaryforum.com/forum/showthread.php?t=2941&highlight=control+failure&page=3

[James]

I have a round tube coming out of the front of my torque tube on my Bensen style rotor head, it turns 90* down, I can fly my gyro with this little tube, practice all the time.

James Lee

[Jazzenjohn]

How about posting a picture of it James? Let us know what the dimensions are, how well it works for you, and what you'd change, if anything.

[fiveboy]

My gyro is a tandem. The control rods are way in back of me. My question is posted in the piloting technique area to see if there is a piloting technique that might work (other than grabbing ones ankles).

I will read the posts alluded to but Im guessing they may have to do with a single seater....?

[MikeBoyette]

Years ago there was an old mac pilot named Smokey. He refused to put jam nuts on his control rods. He told others that he often practiced flying the gyro by placing his hands behind him and flying with control rods in case anything ever happened. Well one day he was flying and he lost the contols. This was witnessed by Chuck and others. They saw him trying to control the gyro behind him to no avail. He ended up crashing and was killed.

[brett s]

Think I'd spend more time simply building & maintaining a primary set of controls correctly. None of the certified helicopters I've flown had backup controls, and the only failures I've seen were related to either poor maintenance (forgetting to both tighten & cotter pin a nut, or leaving a nut off entirely) or catastrophic failure of something nearby.

An example of the latter I remember was a CH-47 that had a #1 engine transmission come apart, the aluminum push-pull tubes for the aft rotor run right next to it & were both destroyed. The Army actually came out with a mod kit to replace those two tubes with stainless steel ones in the whole fleet.

Strange but true - a few years later there was a series of in-flight fires in the then fairly new CH-47D's, in at least one case aluminum flight control pushrods burned through before they could get the aircraft on the ground. They couldn't ground the entire fleet, so we had a series of interim fixes - including fireproof paint (that instantly disintegrated when exposed to hydraulic fluid, and Chinooks were notorious leakers) on all the control tubes to buy a couple more minutes, then firesleeving over that because it'd last a bit longer & finally stainless tubes in that whole area.

[Alan_Cheatham]

Ron Herron developed a triple-tube control system for his Littlewing, loss of one tube still allowed control.
.

[EI-GYRO]

A short overhead stick will provide a backup if the rods fail.
Otherwise Ron Herrons redundant rod is a good idea.
I have also seen an arrangement where one pushrod controlled roll,
and the other pitch, so you wouldnt lose both axes together.
I think Paul Bruty implimented a separated roll and pitch control on his
Firebird.
My own feeling is that a control system which loses control totally
in both axes due to a single-point failure is lousy engineering,
particularly in a vibration-rich environment.
And totally unnecessary.

[fiveboy]

Im confused. Which (left or right) does the center control affect.... or is it somehow slaved to both?

Is there a material that is less prone to vibrational wear than the aluminum we use? Isnt stainless more brittle?

The spot on the other thread referenced here #33 at http://www.rotaryforum.com/forum/showthread.php?t=2941&highlight=control+failure&page=3 where the lower push tubes join to the 'yoke' below and transfers (ultimately) to the stick is where I have particular concern.

[GyroRon]

Maybe the thing for us tandem drivers is to invest in a backpack parachute, like my friends wear in their aerobatic airplanes, and in the even of a loss of control, we shut off the engine and bail out....

[fiveboy]

Ron

Its a good idea but I think the explanation to the passenger will be a tough one.

[karlbamforth]

The third rod effectively supplies a hinge point not dissimilar to the helicopter rotor control Dennis posted pics of not long ago.

[bones]

I can send some photos of what happened to the Magni recently if you like, not pretty.

[Tex~N~Oz]

Maybe the thing for us tandem drivers is to invest in a backpack parachute, like my friends wear in their aerobatic airplanes, and in the even of a loss of control, we shut off the engine and bail out....

It's hard enough to chunk someone out of a plane that's expecting it, much less someone who's:
1. not tied to you
2. not expecting to have to jump
3. in a state of panic

You'll find they'll ride the ship down and as the captain, you'd wish you had of also if you live and they don't. Unless of course you only take up skydivers who would just love a chance to jump. ;)

I'm still working on the BRS system and hopefully will have something to show in a few months.

BTW when is that bub coming??

[Resasi]

Nicolas you mention a short bar from the front of the rotor head. Is that it?

Sounds simple and a good precaution/back-up.

[Aviomania]

Nicolas you mention a short bar from the front of the rotor head. Is that it?

Sounds simple and a good precaution/back-up.

yess.....its one way of doing it.

[Gyro_Kai]

There was an accident once with control rod screw breaking.

The result was, that the pilot had cyclic left right but not fore-aft. By gradually autorotating down, Pilot and passenger survived with bad injuries. Later this was discussed and suggested to use the trim system for a controlled descent with airspeed. However, how you then flare with the delay of the pneumatic trim in the MT is still a mystery to me. Alledgedly it can be done, if practiced beforehand.

Kai.

[EI-GYRO]

I'd love to hear a detailed explanation of that, Kai.
If one pushrod fails, for whatever reason, you have one pushrod and the trim spring
still operating.
I cant see how you would have any coherent control over the machine with
that combination.
There has been one case, at least, where the control system detached from
the keel, and the pilot landed with trim, throttle and rudder, but that is a completely
different kettle of fish.
Ron Herrons's third rod should provide sufficient redundancy for most pessimists.
If I had a parachute in a gyro, I'd throw the parachute away before I'd try to
use it. Unless the rotor detached, of course.
In which case, I'd still be trying to figure it out when I hit.

[Resasi]

I think I am beginning to get the grasp of 'Inshala' ( If Allah wills it.)

Heard it a lot in the ME. Used to laugh at it until I got into gyros.

It now has acquired both resonance and a new understanding of the expression

[Gyro_Kai]

I'd love to hear a detailed explanation of that, Kai.
If one pushrod fails, for whatever reason, you have one pushrod and the trim spring
still operating.
I cant see how you would have any coherent control over the machine with
that combination.
.

Fergus, you can control the pitch by trim alone. If one push-rod is still attached, any stick action will result in roll-change. So I guess it works a bit like the 3-rod model discussed here. ONly that the 3rd rod is operated with the trim switch rather than the stick.

Kai.

[Alan_Cheatham]

Ron Herron also developed a redundant control system for his two place ships, including Andy Keech's LW-5 "Woodstock", which used dual Teleflex/Morse cables on the pitch and roll axis. Based on their mechanical specifications and when using these types of cables on a gyro's primary controls I feel that dual cables are a wise design decision.
.

[Alan_Cheatham]

I consider this to be an unwise design decision on any gyro but especially on a heavy two place ship.
.

[Tex~N~Oz]

Alan, I agree that the one cable hub is a very bad idea, but I feel that ANY guided cable system is an accident waiting to happen..
I used to boat race and we'd use these types of cable for the rudder. One day after a run I lost all steering and drifted into place.. Thankfully I'd already lost my speed and the drag chute was out. Upon inspection we found the cable had slipped from it's bracket and had landed on the hot exhaust header, melting the guide, allowing the core to spring out and become ineffective for control..
While the dual cable system is better for redundancy, what happens if one of the cables locks up?? This system is good in case one of the cables fail, but that's not as likely to happen as opposed to binding.
Now you've doubled your chances of that happening and it's fairly common.
Nothing will beat the ole pushrod system...

[EI-GYRO]

Apart from an overhead stick.

[Doug Riley]

Here in the northern U.S., we have sub-freezing temperatures more than half the year (at night, anyway). A hazard of Teleflex cables is the accumulation of water in sags in the housing (like a plumbing waste-pipe trap). The water freezes and locks up the controls. Since it's colder at altitude, it is possible for the controls to be free (water to be liquid) on takeoff, only to freeze up during flight.

OTOH, an overhead stick made of cold-bent 6061-T6 is not immune from cracking -- especially at the upper bend just outboard of the torque bar. It has happened. I used an internal sleeve on mine for the upper half of its length. Others have installed a light, clamp-on brace across the upper angle of the stick, to triangulate it and reduce flexing.

I like the 3-pushrod setup, using aircraft-quality rod end bearings.

[DennisFetters]

But am I alone in thinking about, what would I do if some part of my control rod system were to detach rendering my stick useless?
ok guys..... now what do we do?

Realistically, just hope you are not too hight at the time...... less time to ponder it.

[fiveboy]

Realistically, just hope you are not too hight at the time...... less time to ponder it.

This is analogous to a comment my CFI made when I asked him how you land at night in an emergency. He said, You know the landing light? You turn it on and look down. If you dont like what you see.... turn it off!

I still laugh at that.

Yes well at the end of the day I suppose as we have all agreed all over this forum, it comes down to good preflite and good training and after that.... good luck!

[birdy]

If you dont like what you see.... turn it off!
Gota remember that one. ;) :)

[John Evans]

Any solution to this problem should be simple and easy to apply. While the control rod ends are not the only source of a control failure they are the most obvious and likely. Ron Herron's excellent 3 rod solution is good, but unlikely to be applied to existng machines, the accessory overhead stick would be easy to fit, but requires practice at reverse control inputs. Good preflight inspections must be regarded as essential, but may not detect a hairline crack in the neck of a rod end.
A solution I have used (no it's never been tested by a rod end failure) consists of a strap around the rod end anchored to the 3/16 bolt that holds the threaded slug in the end of the control rod. The actual material of the strap is not important as it only gets stressed in actual failure and the resulting slop in controls should make most people anxious to land without delay.
This simple modification may have prevented the recent loss of a Butterfly in Tasmania, if it can't be recovered from deep water subject to tides and river currents we may never know. The pilot was very fortunate to have survived.

John Evans

[EI-GYRO]

John, It would be very interesting to have an account from the pilot of that
machine, about the behaviour of the machine during the event. Is this available?

I believe there is no coherent control capability remaining once a pushrod has parted,
but this appears not to be the only view. I would like to know.

If people wont apply Ron Herron's redundant pushrod, then your 'loose-link' solution
should maintain a workable level of control.

Lastly, the issue of 'control-reversal' with an overhead stick, or a short 'accessory
overhead stick, while technically correct, is, in practice, not the case.
It is far more akin to steering a car with your hands on the bottom of the steering
wheel. Not a big deal.
The accessory overhead stick is different again, given that the inputs are all
vertical, but similar logic applies.
I have tried all three, (the accessory only on crowhops), and while the control force
feels a little heavier on the accessory stick, I see no reason why any pilot, with a
little practice, could not easily make good use of it in an emergency.

But I really would like to hear about your event in Tasmania, as most pilots seem
not to survive these occurrances.

Fergus Kavanagh.

[Alan_Cheatham]

Lastly, the issue of 'control-reversal' with an overhead stick, or a short 'accessory
overhead stick, while technically correct, is, in practice, not the case.
It is far more akin to steering a car with your hands on the bottom of the steering
wheel. Not a big deal.

Without some practice the control inputs into an overhead stick would be confusing to a pilot only accustomed to a control stick, so practice is the key to using an emergency overhead stick. That can easily be obtained either on the aircraft itself or using a flight simulator, such as X-Plane, and mounting a joystick upside-down to something, like the computer table. Then hours can be spent safely practicing to allow the brain to adapt to the "reversed controls".
.

[Mac]

Sorry for the hijack Fiveboy

Another one for Birdy (Post 35) if you have not heard it before -

Confucius say: Pilot who fly gyroplane upside down have nasty crack-up.

[fiveboy]

Mac no sweat. Confucius needed to solve inscrutable dilemma!

BTW guys.... I like the strap at the idea anchored to the bolt in the slug. I suppose if the faiure is anywhere along the push rods your ticket is just punched.

[karlbamforth]

Gentlemen,

I am not sure that a loose/sloppy link is the answer here.

Ideally the best thing to do is fit aircraft standard rod ends. Fit them correctly so that there are no bending loads applied, especially to the threaded portion and ensure they are correctly locked. Maintain them correctly and there will be almost no chance of failure.

If you roll a gyro or have a blade strike, replace all rod ends. If you buy a gyro from someone else replace the rod ends, you do not know their history.

I think we all agree the third rod system would be preferable if we want redundancy.

At first glance the loose or sloppy link system appears preferable to a complete disconnection.

Think about what will happen in the event of a rod end failure.

There you are flying along with a very responsive machine, suddenly you are in massive PIO. Half your brain is trying to regain control and half is wondering what the hell happened.

The loose link will cause such a delay in the flight controls that PIO will be almost impossible to avoid. Roll inputs will have a big delay, pitch inputs will probably generate a rolling climb/rolling descent with a big delay.

In the few reports I have seen of a flight control disconnect the occupants were able to fly the aircraft to the ground only loosing control while trying to land. This seems more survivable and a lot less scary than the loose link scenario.

Any thoughts anybody ?????

[John Evans]

It would probably be inappropriate for me to try and give much further information on this event, but I can give you some.
The Butterfly was operating at about 300 ft above the Tamar river, a bang was heard, apparently followed by further noises, the stick became ineffective and the nose went down, increasing and decreasing power made no difference to attitude, it is said to have hit the water inverted. They will be very lucky if they find the wreck.
Presumably a rod end failed.
Butterfly flyers might be prudent to ground their machines until further information is available.
Having suffered a complete control failure myself while instructing in a gyroglider I can sympathize with the pilot, in my case the rear main pivot in the control system let go, it had recently been stripped and inspected but the fault was missed. It was not a fault that could be detected on preflight.
I was fortunate in that my student was fairly chubby and provided me with a cushioned landing, we both only had a few bruises.
Obviously the straps would have not been helpful in my accident, but they are a light, cheap, easy safety measure. The neck of a rod end looks like a weak spot to me!
Those familiar with James Reason's ( a British expert on Human Factors in aviation safety) "Swiss Cheese" model will understand that when a threat to safety is encountered multiple layers of safety precautions can prevent an accident if the holes don't align.

John Evans

[John Evans]

I have just noticed karlbamforth's post. I believe it misses an important point. Surely we are all trained to respond to anything resembling PIO by reducing power and easing the stick back. if that back pressure is maintained and the gyro is flown "behind the power curve" slop in the system should be minimal.
Obviously the other measures he outlines are good, but as he points out they only reduce the chance of failure, there is still no extra layer of "Swiss Cheese", a failure is still catastrophic.

Johyn Evans

[PW_Plack]

The loose link will cause such a delay in the flight controls that PIO will be almost impossible to avoid...

There will be mechanical play, or slop, in the controls, and the link might not last long under vibration, but what would cause any additional delay in control response?

[karlbamforth]

I have just noticed karlbamforth's post. I believe it misses an important point. Surely we are all trained to respond to anything resembling PIO by reducing power and easing the stick back. if that back pressure is maintained and the gyro is flown "behind the power curve" slop in the system should be minimal.
Obviously the other measures he outlines are good, but as he points out they only reduce the chance of failure, there is still no extra layer of "Swiss Cheese", a failure is still catastrophic.

Johyn Evans

That is quite right John but pilots are trained to deal with PIO caused by the delayed response of gyro flight controls. Obviously it depends upon how much play there is in the system, but this would go from normal response to sudden unexpected PIO. In a HTL gyro it would only need to be there for 2/3 seconds before PPO became the dominant force.

Control rod ends are much stronger than you think. Most control failures will be caused by bad assembly rather than failure of a rod end. Human factors show that introduction of a loose link gives you one more thing to incorrectly assemble, it may detatch and then jam your good control rod end. Its all a matter of calculating the risk, the risk of failure may be lower than the risk of the loose link jamming your controls.

I work on the Diamond DA40. Diamond deliberately bent the control rod ends on the flap and aileron system (don't ask me why) and they worked fine for the last 4 years without a failure until Diamond produced a revised control system that did not need the bend. Last year we flew nearly 20,000 hrs on Diamond aircraft with no sign of a rod end failure.

[karlbamforth]

There will be mechanical play, or slop, in the controls, and the link might not last long under vibration, but what would cause any additional delay in control response?

I might be wrong Paul, which is why I hope others will jump in.

In my head as I tried to imagine what would happen. Sloppy controls will tend to allow the aircraft to wander, with the pilot chasing it, this as I understand it is the lead up to a PIO event. With the normally reliable aircraft going from very responsive to suddenly over and under controlling with the pilot chasing it with sloppy controls, I can see it getting out of control very quickly.

I once saw a FW pilot who had a partial failure of a control system, the aircraft suffered violent pitch changes. The pilot managed to land the aircraft but it was so badly structurally damaged as to be not worth repairing. Most of the damage was caused in the air not during the landing. I know its difficult to compare FW and rotary but just 1-2 seconds of a similar event would destroy a gyro.

As I say I may be imagining it all wrong. I still stick with the prevention is better than straps cure tho.

[OzyRuss]

watching this thread........seems to me, that a "morse cable" system may be the better way to go.............yet to ever hear of a failure

:noidea:

[fiveboy]

watching this thread........seems to me, that a "morse cable" system may be the better way to go.............yet to ever hear of a failure

:noidea:

Please elaborate.

[Mike Schallmann]

"Morse" is the name of a company that builds push/pull cables. They are used extensively in the Marine Industy as control cables for steerage -throttle-shifting etc....

They are very reliable --but they do have some "slack " in them --Thats why they are often used in pairs when precise control is necessary--

[OzyRuss]

Mike........that may have been yrs back, but definately not now.

The single push / pull cables are indestructable now, and adjusted right, zero slack.

More and more guys here are useing them..........love em.
Guy here makes the retrofit cyclic stick, and head gizmo components.

This system ( morse ) long used in marine.......( harsh enviroment, thats for sure ) is now standard fit out in marine.

[EI-GYRO]

Thanks John.
That is the point I was trying to get at.
The weakness in the compound pitch/roll function of the standard gyro pushrod
seems to be that no useful pitch or roll controllability remains in the event of
one pushrod disconnecting, for whatever reason.
It would seem to me that in the event of the left hand rod disconnecting,
the stick would go full left instantly, and pitch fore/aft movements of the stick would
be ineffective.
The pitch effect would then be dependent on the trim spring? I'm not sure.

That is why I dislike the compound pushrod arrangement.
I dont see what advantage the compound arrangement has over individual pushrods for
pitch and roll. Symmetry is pretty but is it always a good idea?
Am I missing something?
Ron Herron's redundant pushrod provides redundancy in both axes, and effective
separation of pitch and roll functions.
The accessory overhead stick suffers from the problem that the pilot would be in
the position of trying to recover from an unusual attitude, before he even gets to
start a controlled descent. This might be too much to expect.

I have voted with my feet on this one, and I use the overhead stick, as I have never been happy with what I perceive to be the weakness of the compound pushrod
arrangement in a vibrating system.

Yes, an overhead stick can break too, but it should, if the pitch trim spring is set correctly, allow a reasonably controlled descent on throttle and rudder.

I'm not aware of any successful recovery from a broken pushrod event at any
significant altitude. Can anyone point me at one.?

John, will the event you refer to be the subject of a report at any time, as I
would like to see it, if so.?

Cheers,

Fergus.

[John Evans]

Yes Fergus,I presume there will be a report at the appropriate time, unfortunately it will only be definitive if the wreck is found. According to my information a rod end is the current suspect by those on the scene. Hopefully the Butterfly doesn't have some yet to be discovered weakness that is the real cause.
I see Morse cables are being promoted on this thread, while they have been used by some for years and do have their enthusiasts they would probably be best used in pairs to give that added layer of "Swiss cheese" I mentioned earlier. They can then be adjusted against each other to remve any of the inherent slop that comes from running a small diameter wire through bends in a larger diameter sheath.
Personally I will be happy to continue flying on good quality rod ends, carefully installed and inspected, but with a safety strap - there's no way it's going to jam the controls.

John Evans

[Greg Mitchell]

G'Day Gents,

Allan spent a considerable amount of money and time trying to locate and recover the Monarch from the Tamar River at a depth of more than 50 meters plus in the shipping channel.

Some think it was a left sided top rod end, the push rod, which made its way back into the prop.

You can read more on the ASRA website in the accident section. Allan will be making a full report in the next day or two.

In fact Allan was at 1050 feet, some 300 meters not 300 feet. He went in at 90 degrees or slightly more inverted. If he'd been flying at home he would have been over land....., if he had another 50 feet of altitude, the blades may not have punched a hole in the water for him........

Not only did Allan survive the impact but he survived 15-20 minutes in the Tamar River, when they pulled him out his core temp was down to 31.5 dgree Celsius. The river on the tidal in and out flow runs at more than 6 knots and the water appears to boil with 2 foot wide whirlpools and opposing eddies. The river is known to be treacherous by locals.

Here are a few pics.

Mitch

[Greg Mitchell]

Couple more pics.

[Greg Mitchell]

http://www.themercury.com.au/article/2009/04/07/65821_tasmania-news.html

http://www.examiner.com.au/news/local/news/disasters-accidents/gyroplane-pilots-100m-plunge-into-tamar-river/1479984.aspx

http://www.thedaily.com.au/news/2009/apr/10/coast-pilot-escapes-death-gyroplane-crash/

[fiveboy]

WOW that is really hairy reading.... and funny. His comment about having made it and now hes going to drown just struck me as very dry Aussie humor at its best.

[Doug Riley]

A former student of mine who owns a Butterfly reminded me that his original control pushrods were slightly short. This meant that the threads of the rod-end bearings were not engaged far enough. He obtained longer pushrods from Larry.

This might be something to look for in connection with this accident.

[Alan_Cheatham]

Greg,

Were the rod ends on this ship a standard rod end or Larry's special spring loaded rod ends?

[Greg Mitchell]

G'Day Doug,

YES.....my original push rods were short....although the requirement down under is to have at least 1/2 the thread in the slug. This I had. I changed mine out for longer pushrods to.

Allan's craft was somewhat different. The left pushrod was 'spliced' for want of a better term. This done to allow pushrod full range of movement and not foul on the elec starter monted off the front left side of the engine. Also Allan had changed out his rod ends to comply with type cert for his Aussie Monarch. I do not know how much thread he had embedded into the slug. I'll attach a pic of mine.

Also on the OZ ASRA forum are several pics of the MLS under the accident thread, so as to allow for relevant discussions.

Doug I have spoken to Dan, who I believe you are referring to., regarding my experiences with the 503 MLS setup. Mine is the 582 version as was Allan's.

Hi Alan,

We had std rod ends, although mine were the original aircraft grade type. Allan's control pivot, crossover bar and rod ends had been changed out. In fact we have both fitted a 10 gallon seat tank from OZ and the control sticks and seat mounts had been modified to suit. We did our mods independantly of each other and the manufacturer. (Larry)

Hope this helps to clarify.

Cheers,

Mitch.

[Greg Mitchell]

Post from the ASRA website by Allan Wardill the Monarch Pilot.

Gidday Everyone,

Having arrived home in 1 piece, I thought it appropriate that I try to describe my little drama, now that I have coverage and don't have to rely on Mitch for his valuable acess time, something for which I am extremely greatful.

But first, I must offer my sincere appreciation for the well wishes that you all have expressed. It wasn't nice, not helped by the failure to recover the evidence that we desperately need. Your humour is also touching. I p1sst myself laughing. Thanks. So here it is:

I departed the Clarence Point private airfield with Greg “Mitch” Mitchell for a flight to determine the best and safest route for the conduct of a “mass” flyby of gyros the following Friday. This was requested by the organisers of the Three Peaks yachting event due to get under way that day. The participating gyros were to be part of a contingent expected for the annual ASRA National Championships.
Departure into a gusty 20 – 25 knot north westerly was uneventful as was the ensuing flight and dummy fly past. The return route had us tracking north along the western bank of the Tamar River. I was behind and slightly below Mitch at 1000’ AGL, an ideal position from which to observe the terrain and population density in the general area.

About 15 minutes after takeoff, I heard what I can best describe as a mechanical thump that appeared to emanate from the vicinity of the rotor head. This was not normal and I decided to return to the strip as soon as possible. I rechecked the relative position of the strip and the best way to track, avoiding as many houses as possible. Redirecting my attention forward again, I noted that the attitude of the gyro had dropped significantly. I applied corrective back pressure to the control column without observing any reaction from the gyro. The nose continued to drop and by now had reached an alarming nose down angle. Movement of the controls in any direction was ineffective and they felt very “loose” for want of a better term. I tried reducing the engine power to idle with no observed effect. Full power also achieved no response. All I could see in my field of vision was water which was approaching very quickly. I closed the throttle and broadcast a hurried Mayday advising that I was “going in” but neglecting to add a position of any sorts. I then though something like “this looks like it”. I also recall thinking of the Michael Howard fatal accident not long ago, together with “maybe the water will be softer than the ground”. The last look I recall is being in what appeared to be a vertical, if not slightly inverted attitude. I have no recollection of the gyro rotating despite witness reports.

I remember my head, encased in the helmet hitting the water on the right hand side. Next recollection was cold water around my face inside the helmet. I thought now, that having apparently survived the initial impact, I was about to drown. I had fleeting memories of a fatal I investigated years ago in which the pilot survived a plunge into water only to drown after having released his seatbelt but not lasting long enough to get to the surface. I noted that there was a fair amount of light above to my left and proceeded to release the harness buckle upon which the harness fell away. I don’t recall swimming up as such, but found myself sucking fresh air about 40 – 50 metres from the nearest shore. I started swimming in that direction whilst considering things like the water temperature which seemed pretty low, whether or not to jettison my helmet, outer clothing and gym shoes. As these did not appear to be “dragging” me down, I chose to leave them in place and remove them later if they became a hindrance. I was unaware that the crash had been witnessed and when I saw people on the shore, I yelled and waved to attract attention. My cries were acknowledged and I alternately breast and back stroked towards the shore ……. so I thought. The strong current was carrying me towards the mouth of the river and further away from the rescuers who were trying to launch a rubber duckie. As I swam across the outbound current, I moved into a reverse eddy area and began tracking up river. At least this would keep me in sight of the would - be rescuers. After what appeared to be a long time, I observed a speedboat approaching my position. I waved and waited. The driver helped me to lie across the transom and motored the remaining 30 metres or so to shore. The Police, responding to a 000 call had commandeered a tinnie and arrived shortly after I climbed onto the jetty. A quick check by the ambos noted no apparent significant injuries although the thermometer said a core temperature of 31.5. I shivered and chattered into a car that deposited me at Mitch’s home where the warm shower felt pretty good.

Despite some 18 hours of searching with some of the latest side scan mapping sonar equipment, the gyro has not been found to date. The average water temperature during these operations was around 15.5!

No doubt, the speculation regarding the possible causes will continue and provided it is constructive it is very positive. I noted a couple of questions previously in this thread and advise that the gyro was strapped to the back of the custom F350 tray by the main and nose wheels only. The control stick was secured loosely in the approximate level flight position such that there was no strain or stress on the control system. The head though, could move from stop to stop left and right without effort.

It is obvious to me that a control failure occurred, but exactly what and why is the mystery.

Thanks again.

Regards,

Waddles/Puddles etc!!!!

[Greg Mitchell]

My response to some questions placed on the ASRA forum.

G'Day Des and all,

The MLS unit is bolted to the torque tube via 4, 1/4" AN bolts with thick nuts. These bolts go thru two 6061-T6 plates and thru the torque tube. The Crossover bar is 4130 heat treated to a Rockwell hardness of 38-40. The rod ends are aircraft grade.

Allan's setup may have been different, ie: rod ends, crossover bar and control pivot.

Nevertheless, You question Des is very relevant. It is pure speculation but the possibility exists that the MLS may be party to the accident. However, I have racked up many hours now on the MLS. Far more than Allan has. My MLS has done approx 40 hrs, without any turning of the belt.

I had initial problems at the engine end of the MLS, though extra through bolts on the pull start have rectified that situation.

Tests on my craft show that the left push rod if let go from the top, can fall back into the prop. This can not happen on the right hand side due to the air intake silencer. I suspect then that if the entire MLS unit were to brake off at the torque tube, then there is the possibility of the unit being hit by the prop.
What is the likelyhood of the torque tube breaking off?

If the crossover bar broke in half, then the left pushrod would likely hit the prop. The right would not.
Again what is the likelyhood of the heat treated 4130 crossover bar braking thru at the 2, 1/4" bolts?
Would a mild steel crossover bar of slightly larger section fair better?

Murray Barker noticed that at certain rrpm, there can be a shudder thru the MLS system. This is operator error bought about by advancing the throttle beyond 2600 engine rpm before the rotors reach 140 rpm. Ideally at 2600 rpm the centrifical clutch will throw the bendix. The blades then reach 140 rrpm at that setting within 8 seconds. Then the operator advances the throttle slowly and evenly to the desired rotor rpm is reached. The shudder is the result of belt flap within the system caused by operator error.

I am posting pics for you blokes to look at and provide opinions and thoughts on this matter.

The recovery of the craft is not likely now, though I will be looking for it every time I fly.

Cheers,

Mitch.

[ke5wv]

Hello All,
The aluminum inserts that Dana supplied me for my control rods have a threaded steel sleeve (about 5 threads long) into which the rod end screws. I often wonder if this is more or less safe than screwing the rod end directly into a threaded aluminum insert that has the same thread depth as the rod end? Any thought on this would be appreciated.

Thanks Thomas

[bpearson]

Any inflight adjustable trim fitted?

[Alan_Cheatham]

Hello All,
The aluminum inserts that Dana supplied me for my control rods have a threaded steel sleeve (about 5 threads long) into which the rod end screws. I often wonder if this is more or less safe than screwing the rod end directly into a threaded aluminum insert that has the same thread depth as the rod end? Any thought on this would be appreciated.

Thanks Thomas

Do you have any specs on the insert used?

[Doug Riley]

Greg, yes, Dan LeCuyer is the person I referred to. Just chatted with him yesterday.

How exactly was the left pushrod "spliced?" Did it have a crook in it, an upper and lower pushrod with a scissors arm in between or...?

The Metro-Launch is quite a powerful prerotator, but also an awful lot of iron to hang off the back end of the torque bar. We found on Dan's machine that the MLS weighed enough that the trim spring could be slacked to zero tension, and even then you had to hold a bit of forward stick pressure at cruise. Of course, all that weight is supported by the pushrods in their "weak" direction (compression) any time the head is off its aft stop.

A typical gyro control pushrod tube has about 200 lb. of compression strength if it is straight. Much less if it's bent.

[Greg Mitchell]

G'Day Doug,

Thanks for those figures and insight.

See attached configuration of Allan's left push rod setup.

Cheers,

Mitch.

[bpearson]

Don't like that Greg!

[NoWingsAttached]

Got a notion for you, someone out there. I was always told that any bolt needs only to be threaded, as a minimum, depth = diamater. After I crashed, I inspected all the ball joints that failed and the ones that bent without failure. I believe from this inspection of failed vs survived heim joints that there is a misconceived notion about the strength of a fully inserted/threaded bearing vs one that is tNOT hreaded in fully. THe joints that were NOT fully inserted are the only ones that survived, meaning the weak point on the joint - the transition from threaded part to ball joint part - is forced to take all the stress.

By allowing room for the bolt to flex a bit it seems the whole piece is more tolerant in stress and does not fracture.

I think it might be wise to thread a ball joint so that at least 3-4 threads, perhaps even a few more, remain outside of the slug it is threaded in to.

I'd bet dollars to donuts there has never been a failure of the threaded bolt shank on any Heim joint.

[Greg Mitchell]

Gerg,

Interesting observations, thanks for that. When I lengthened my push rods to have more of the rod end embedded, I ended up with about 2-3 threads extending above the thin lock nut, then I tweaked some tie wire above each lock nut. Prior to Michael Howards passing in the Magni (push rod/rod end issue) my rod ends were only half way embedde into the slugs, although this is acceptable as the bare minimum, I very quickly changed my setup.

Gerg, Tim Mac tested rod end of various types to destruction. He posted some stuff somewhere recently. Perhaps Tim would post it here as well.


Brian,

Ground adjustable trim only. Allan never did like the spliced push rod. I do not have that on mine as my 582 is a pull start.

Cheers,

Mitch.

[karlbamforth]

Got a notion for you, someone out there. I was always told that any bolt needs only to be threaded, as a minimum, depth = diamater. After I crashed, I inspected all the ball joints that failed and the ones that bent without failure. I believe from this inspection of failed vs survived heim joints that there is a misconceived notion about the strength of a fully inserted/threaded bearing vs one that is tNOT hreaded in fully. THe joints that were NOT fully inserted are the only ones that survived, meaning the weak point on the joint - the transition from threaded part to ball joint part - is forced to take all the stress.

A longer threaded portion simply has more material to bend than a short one, giving a larger bend radius for a set bend angle. So no suprises that the shorter ones failed first.

Unfortionately it doesn't help much looking at components that have failed from bending loads when they are only designed to be operated in a push pull direction. There should be no bending loads on control rods when operated. They should ideally be straight with no bends in them.

[Greg Mitchell]

RESPONSES TO QUESTION'S on the ASRA FORUM

"Peter,

Yes the brake will engage at full forward stick.
The torque tube is specially designed to give 6 degrees of forward movement past the horizontal, this then allows for brake engagement past this horizontal position.
We have been told, It is unlikely the stick and torque tube would be situated forward of horizontal at any point in flight.

If by self governing you mean, that at some stage it would have settled out into a fixed nose down position, then NO!
The angle of the dive was not self governing.......the Monarch kept nosing over to the point of impact which by all accounts was at 90 degrees or slightly inverted.

Ken,

The torque tube is specially designed to work with the slider head and MLS system, allowing for the use of the brake system also. So yes it was a new torque tube, that to my knowledge had not been flapped or had any other damage etc.

My rod ends are aircraft grade. Allan's had been changed out to what the QLD fellas use as std. This was done (along with other mods, Cross over bar, Tail stops at about the 30 degree position etc) so as to allow single place type certification (dont hold me to the phrasing of that).

Gents,

One eyewitness report suggested that Allan's rotors were slowing and the body of the aircraft was rotating. Also another reported the 'clatter' was being heard all the way to impact.
We have been told that if the blades were slowing then they would indeed nose over.
Also if the trim spring had moved from the right hand 2 O'clock position back to the 12 O'clock position this may have accounted for the lack of control feeling, as the trim was ground adjustable only.

There is a lot of discussion going backward and forwards between, big hours pilots and other manufacturers, including Larry.

Several theroies abound and all are speculation only. Whilst it may never be known for certain a very good understanding of what may have happened is beginning to develope.

I certainly appreciate peoples views and insight as I fly a similarly configured craft.

Thankyou.

Mitch."

__________________________________________________ ___________________

Post by Allan Wardill on the ASRA Forum

" Giddday Again Everyone,

Having mulled further over the possible failures and having taken numerous measurements on the 2 remaining Monarchs in OZ and had discussions with Larry, I provide the following for further speculation:

Witness report 1: From about 1 - 1 1/2 km away, saw the steep descent of the gyro which appeared to be rotating in a direction that he could not determine.

Witness report 2: From about 400m from the impact site, saw and heard the whole event. He states there was a distinctive rapid "pop, pop" followed by a clattering that continued until impact. He didn't notice the gyro turning or spinning.

Theory 1: The upper left rod end failed allowing the control rod to rotate backwards contacting the propeller, the "pops" being consecutive prop blades (Brolga 4 blade) hitting and cutting off the end of the control rod at a position such that the end of the remaining control rod contacted each prop blade as it passed (the clattering).

Against: The trim spring should have had some effect in precluding the abrupt nose down flight path. It didn't. This would however, explain the "lightness" of the controls and the apparent no effect that their use had.

Theory 2: The Revolution rotors had been assembled such that the strap bolts were inserted with the heads of the bolts on the top side and the nylock nuts on the lower side. I completed the assembly personally immediately before this flight. As these blades were my "travelling set", I had not used them for at least 2 years. The usual blades were manufactured by Peter Barsden and were the ones fitted when the MLS system was fitted and signed off by another TA. When the bolts on Mitch's rotors were inserted in this manner, at near full teeter, the nuts struck the MLS housing!!!!!!! In discussion with Mitch, I explained that by convention, bolts are fitted down from the top. In this case however, the blade manufacturer states that the bolts should be fitted from the bottom up to allow for greater clearance from other head components!!!!!
With the above in mind, I speculate that due to very gusty conditions even in straight and level flight, it may be possible to go "negative" unintentionally for suffucient period of time to allow the rotor speed to decay enough such that near full teeter of the blades occurred. The "pops" were the inner strap nuts of successive blades striking the MLS bendix housing causing it to bend clockwise when viewed from the rear. The second strike caused the housing to contact the ring gear on the upper right and lower left edges (the clattering). Once this occurred, the blades immediately started slowing and the gyro would have rotated to the left. As the rotors slowed, lift was lost and the nose dropped irrespective of the trim spring which may have been displaced anyway. Similarly, the loss of rotor speed would have caused the rotor blade to lose it's gyroscopic rigidity thus rendering any control inputs ineffective and causing the controls to feel "loose".

Against: It is not possible during straight and level flight for the rotors to teeter anywhere near the teeter limits.

That's as far as we've got to date. Mitch is going to do some more angular measurements to determine on his gyro, exactly how much teeter is required before the nuts contact the MLS housing. I expect it will be less than the 6 degrees we normally see.

Regards,

Waddles. "

__________________________________________________ _____________________

Post by me on the ASRA Forum.

"G'Day All,

Thanks Allan.

I am attaching a picture of the MLS with a red graphic line indicating the line a break would likely take if it were to do so. NOTE, there is no eveidence that the torque tube broke.

Please note, trim spring would still be in place and so to are the pulley straps either side.

I do not believe the MLS unit could make it's way into the prop, whilst attached at three points to the mast.

The prototyping of the Patroney Blades on the Monarch MLS system required the installation of 1/8" thick teeter stops, so as to give clearance to the underside strap bolt head from the top of the MLS Bendix housing.

If the norm for a Bensen head is 6 degrees of teeter either side, then the new teeter stops have effectively reduced this amount. By what? I am not sure till measurements are made. It could be in the order of 1-1 1/2 degrees. Thus the amount of available teeter may now be 4 1/2 degrees. Whilst approximately +-2 degrees is required for normal flight, I find it quite conceivable that during a negative event, rotor rpm could decay enough to cause the blades to teeter more to try and equalise lift.

Now the available amount of teeter may be 4 1/2 degrees, however if the strap bolts are inserted from the top, the amount of thread, fat nut and double 0.0063" washers is considerably more than the clearances allowed for during the install of the teeter stops and original prototyping. Perhaps as little as 3 degrees would have been available, before the thru bolts on each strap may have contacted the MLS housing. As each bolt thread and thick nut have impacted, the MLS Bendix housing on top of the MLS unit would have taken an almighty hit, twisting the housing to the right and impinging on the large flywheel. This may have bitten in more and more reducing blade rpm dramatically. The induced friction now causing the airframe to rotate to the LEFT.

Brian I think you might agree that S & L in a blustery 30 knots of wind with those bolts swinging past the MLS housing with the bare minimum of clearance, is a little closer to the limit than even you might like.?

If the blades are slowing, they are not generating the lift, the gyro is dropping rapidly.
As the blades are no longer flying, the gyro noses over. Look at the angle of your gyro in a hang test.
Once the blades are no longer flying, stick inputs are likely rendered useless and unresponsive.

Someone recently said if you were doing a vertical decent, left spiral, the stick can feel like it is unresponsive. This is hearsay and I personally have never tried it.

Anyway Fellas, I don't think the torque tube broke off at all. I don't believe there is any inherent problem with the Butterfly Monarch design. I also don't believe a push rod/rod end let go. Although it is speculation, I am almost certain given Allan's account, eye witness accounts, (both of whom have seen me flying locally on a regular basis) and several high hrs gyro pilots views, that the visual and audio recollections of all coincide quite reasonably with Allan's account.

As Doug Riley on the US forum says, there is a fair hunk of metal hanging off the rear end of the torque tube, however it is supported by the push rods when the head is off the rear stop. Each average push rod able to carry some 200 lbs in compression. The torque tube is rated and engineered to handle much more than that. Also this torque tube is not a std Bensen tube and the manufacture claims it is indeed stronger.

I will be flying my Monarch with complete confidence as I did during the ASRA 2009 Tasmanian National Championships.

If Murray sends me the rod end strap mods, then I will install same. However, I am not particularly concerned nor convinced that was the problem.

I appreciate everyone's views on this. Keep em coming.

Cheers,

Mitch"

__________________________________________________ ____________

[Doug Riley]

Greg, that splice is the structural equivalent of putting a couple of kinks in the tube. Compression forces act along one straight line. A kinked column isn't a column anymore -- it's loaded in bending rather than in pure compression. The short bridge piece is trying to bend out, away from the centerline of the pushrod, when the rod is loaded in compression. It tries to bend the other way when the rod is loaded in tension.

This isn't necessarily the cause of the crash, but it is suspect.

Never put bends (or lap-jointed splices) in control rods, especially near their mid-portions where they are most likely to kink anyway. If you must route around the engine or something, use scissor arms or change the mounting arrangement.

[Greg Mitchell]

Thanks Doug,

Here is the latest page off the ASRA forum.

http://www.asra.org.au/smf/index.php?topic=2598.msg19144#new

I will paste your post on the ASRA.

Thanks Mate.

Mitch.

[Greg Mitchell]

Doug and others,

We would be very interested in your thoughts on the reduced amount of teeter and thoughts and conclusions drawn from comments made above.

I have my daughter and grand children arriving today from the mainland so blading up and measurements will have to wait a day or two. But I will add photos and measurements soon.

We appreciate the input.

Cheers,

Mitch.

[C. Beaty]

We would be very interested in your thoughts on the reduced amount of teeter and thoughts and conclusions drawn from comments made above.



Cheers,

Mitch.You’re most likely to experience the effect of insufficient teeter travel at liftoff.

A rotor doesn’t reach full operating rpm until a couple of seconds after full load has been applied. During those few seconds, the rotor will bang the teeter stops pretty hard if there’s insufficient travel.

[Greg Mitchell]

Yes Chuck. We had a fella's gyro get launched off an upramp at the end of the strip afore his blades were flying properly and high speed blade flap ensued. Good piloting or good luck got him and a young passenger back on the ground safe and sound.

Could you comment on the reduced amount of clearances and teeter available given the discription above. Bare in mind, that we departed in 20-25 knots and it was blowing 30 knots or more on my return to base.

Birdy has made comment on the ASRA site which indicates he thinks it is possible.

At this time I have folk thinking/saying its the left hand push rod only.....and other thinking/saying perhaps the torque tube broke at the bolt holes where the crossover bar is.

Just been to see my Dr and he says 'my heads not on straight'. LOL!

Cheers

Mitch

[birdy]

I often like to marvle at the tips of the disc workn in gusty air. [ i love the self regulating action of the free teeter]
Iv seen the tips jump n dip more n 2 foot from serious wind direction and strength changes on all points of the disc.
I think, all youd need is a combination of low AS, some misstimed cyclic input [ or machine responce],a sudden strong gust on the left side and limited clearance and BANG.
Iv felt the stick kick a few times in conditions like this and the only xplanation i can come up with is the bar tapn the stops. [ and my machines have more teeter room than the machine in question, and it will kick the stops long before it touches anythn else]
IOW, if it CAN touch, it will, in the rite conditions.
[ mum nature has a tendancy to work like that.]
If the bar can touch anythn before the stops at anytime, id never leave the ground till it was fixed.

[Graeme Monro]

Just been to see my Dr and he says 'my heads not on straight'. LOL!

Cheers

Mitch

Don't need a Dr for that advice Mate.

Graeme.

[Heron]

I did not come across this thread untill yesterday . . . :(
Busy and distracted!
But this was a freaky accident and I am glad Allan is whole and dandy! Maybe missing some underwear that´s all . . . :D
Any thoughts on how the cross bar or torque tube could break?
I think Allan´s perception of the flight down to water will be our best set of clues.
Untill we find the machine of course.
Hey Allan, welcome back my friend!
Heron

[C. Beaty]

Yes Chuck. We had a fella's gyro get launched off an upramp at the end of the strip afore his blades were flying properly and high speed blade flap ensued. Good piloting or good luck got him and a young passenger back on the ground safe and sound.

Could you comment on the reduced amount of clearances and teeter available given the discription above. Bare in mind, that we departed in 20-25 knots and it was blowing 30 knots or more on my return to base.

Cheers

MitchWhen you hit the teeter stops in flight, it’ll rattle your eyeballs and leave no doubt as to what’s happening.

Years ago, I had clearance problems with a prerotator and as a temporary fix, installed a pair of ¼” bolts at the edges of the striker plate on a rotorhead built to Bensen dimensions; the bolt heads serving as stops and limiting teeter travel to perhaps ½ of the normal ±9º range.

Each and every time I lifted off, the shaking from hitting the stops would vibrate my sunglasses down to the end of my nose. There was no problem in normal flight after the rotor had reached flight rpm.

[birdy]

When you hit the teeter stops in flight, it’ll rattle your eyeballs and leave no doubt as to what’s happening.
CB, thats abit missleadn.
Yes, if you feed um too much air before they are up to speed at TO, the kick is much worse coz your reaction time and your corrective action [ cutn power] takes time to have effect, and by the time it dose, its well n truely flogn the stops.
In flight, things respond quicker, and hitn the stops is on the outside of the flight envelope, so it takes sum seroius conditions to make the blades just touch the stops. For the blades to hammer the stops, you would have to be in sum serious sh1t, and dumb asa post to not respond, quickly.
Its one thing to push it so's the bar touchs the stops,[ teetering the full 6*] but youd have to push it along way past that to get it to hammer them. [teetering to 7*]

[Greg Mitchell]

Chuck,

I have had inflight blade flap. Smacked the living daylights out of both knees. Granted, the gyro only flew for about thirty meters, should say somersaulted. I tried to horse the thing into the air before it was ready then got hung up on two fences. Complete rebuild.

Mitch.

[mceagle]

Two fences Mitch? - you're a legend. Even Rosco could only manage one fence.

[Greg Mitchell]

Just like drinking Tim, always double up!

Mitch.

[C. Beaty]

Birdy, with Bensen’s full range of teeter travel, ±9º, there is some question in my mind as to whether or not anyone has actually contacted the teeter stops in flight and lived to tell the tale. That would be 9º on top of the typical blade mean angle of attack of 5º or so, more than enough to totally stall a blade.

On my gyro with teeter travel restricted to perhaps ±4.5º, I never hit the stops except at liftoff. But my flying was pretty tame as compared to yours.

Most of the HTL gyros that tumbled out of the air no doubt hit the teeter stops but there are no first hand accounts.
********************
Here’s a contribution you can make, Birdy. Plop down to a landing after rolling out of a tight turn and while the rotor’s still near flying speed, bang the stick around and see whether or not you can hammer the teeter stops. Going from stop to stop of gimbal travel, you can apply 18º of cyclic input in a fraction of a second.

I’ve never been able to hit the stops until the rotor has slowed down quite a bit; until then, it always seems to be able to outrun the stick. OTH, I’ve never tried this on blades that had large pitching moments or had the chordwise CG way out of whack.

[Greg Mitchell]

On my gyro with teeter travel restricted to perhaps ±4.5º, I never hit the stops except at liftoff. But my flying was pretty tame as compared to yours.

Cuck this is approx what Allan and I had on our heads, after installing teeter stops. Allan had slightly more than me.


I’ve never been able to hit the stops until the rotor has slowed down quite a bit; until then, it always seems to be able to outrun the stick.

If the rotors had slowed in a negativeg situation then perhaps with the 30 knot blustery conditions and some stick movement in the wrong direction, could it not be possible that the extended bolts on the strap make contact?

Mitch

[Greg Mitchell]

Chuck and others,

Do you think the torque tube could have snapped off at the 1/4" bolts that hold the MLS plates and crossover bar. It is a sold piece machiuned to give 6 degrees of forward tilt past the horizontal for rotor brake. It has a 1/2" hole drilled into the front about 1/ 1/2" deep and maybe a 3/4" hole drilled into the rear down to about 1 1/2 - 2" back from the
jesus bolt?

Mitch.

[C. Beaty]

I doubt if the torque tube let go Mitch. The greatest load occurs during prerotation; that’s when things that break are most inclined to do so.

But all of this is pure speculation unless the wreckage is recovered.

Properly applied rod end bearings don’t break either. The 3-piece style has a banjo housing, a hardened steel ball and bronze races that are swaged into the banjo housing; lips on the housing are swaged over the races.

I’ve seen the swage fail, allowing the races to rattle around but if the rod end is properly retained with washers on each side, no harm accrues other than a bit of backlash.

The one fatal accident involving a rod end that I have personal knowledge of happened to a friend of mine, Smokey Castner, nearly 30 years ago.

http://www.ntsb.gov/ntsb/brief.asp?ev_id=37027&key=0

Smokey didn’t have jam nuts on the rod end shanks. I constantly fussed at him to install jam nuts but Smokey always replied; “There’s over an inch of threads engaged and I won’t live long enough to pound out the threads on the aluminum inserts.” But he did and nosed into the ground at a steep angle.

[birdy]

Here’s a contribution you can make, Birdy.
Now CB, you know that aint possable.
It WONT land if the rotors are at that speed.

But to the point, i wasnt thinkn bout only pilot input, but a combination of pilot input timed with an unfaverable horisontal wind shear, and maybe even low G.

BTW, how many degrees teeter is happen'n if the blades are deviating more n 2 foot at the tips in S/L flight? [26foot blades]

[mceagle]

A tad under 4.5 degrees I think Birdy.

I have tried to guestimate rotor teeter in rough air flight before and found it impossible to get anywhere near the ball park. The problem of course being no scaleable reference anywhere near the vicinity of the tips. A side on video showed very little movement (possibly only 6" total) in what I thought was really rough air.

We need some smart cove to make up some sort of electronic measuring device to find out for sure.

[birdy]

Lets say 4* for round figs.
Definatly not out of the rhelms is it?

[Greg Mitchell]

Here are a few attachments.

Fly Safe.

Mitch.

[Resasi]

That looks like a very neat Bowden cable set-up Mitch.

Hope the gyro if found.

[fiveboy]

That answers my nagging question of how it would be configured. Was that on the lost gyro or is it anothers?

[fiveboy]

What grade of aluminum (or could it be steel) would those cable retainers be made of. Also, what tool makes that cable crimp/clamp?

TIA

[Greg Mitchell]

The spliced pushrod was on the downed gyro.
The rod end straps are stainless tangs, SS cable and cable crimp. This is an example of a set that have been installed on another Monarch here in Australia.
The crimp is likely done with a Nicopress crimping tool, least ways mine will be.

I think the strap is a little to long and personally I would prefer something that is more closely coupled though still allowing free and unrestricted movement of all push rod/rod ends. (See attached)

Mitch.

[OuterMarker]

I have a question about the heim joint threads. The thread length is 1.25" and 28 threads. Is there a minimum amount of threads which will yield enough safety for the loads imposed on the push-pull tubes?