Domi first flight and incident

[dinoa]

Kosta Giorgiou's new Dominator had its first flight at Agrinio airport last week.
The major departure from plans are that steel parts are stainless 316 1.5mm wall. Engine is a Rotaz 503 with Warp Drive prop. Rotors are RFD 25' with slider head.

I did the test flying as Kosta was just finishing his training with Apostoli Katsougias' in his ELA 07.

Thorough preflight and reconfirmation of hang angle were followed by taxi tests, power checks, prerotations and short hops to where I was introduced to the Domi duck walk that was mentioned by some on the Forum.

First pattern flight was going fine feeling out the controls, no stick shake, straight and level runs at different speeds, 360 turns and then a near vertical sink. Recovery from the sink was by moving stick forward, increasing power then left rudder and stick to stay over landable areas. At this point I noticed that the rudder was locked to the left resulting in a constant left turn. Applying right stick straightened the flight path (track) but with a pronounced slip. At high power settings necessary to maintain height with the slip only turning flight was possible as the rudder became more effective. So I would alternately power climb to the left then slip forward at reduced power trying to unjam the rudder. Something was stopping the rudder at about the 10 degree left position. Full left rudder was possible but no amount of rudder fanning would get past the jam.

I figured there was a good chance I would roll Kostas' new gyro on landing so I picked a smooth soft turf area near the hangar just far enough away to keep people safe in case parts started flying off. A mock approach was made at idle to see how things would line up and it turned out the slip wasn't bad. The wind was also changing due to thermals and I thought if I could do a right crosswind landing at the right moment it would help landing straight. I waited for a gust but the direction would never line up with a good landing area, and the tension was begining to wear me down without the worry of adding another variable.

I redid the mock approach to touch down. Just as before the alignment wasn't bad and the gyro stayed upright as my heart rate wound down with the rotor's.

The post mortem showed the rudder had hung up on the anti-servo tab lever pivot bolt as shown in the pictures. What probably happened is that the pull up before the sink flexed the mast aft tilting the rudder back into the top of the pivot bolt. The bolt head then caught in the hole on the bottom of the rudder deforming it so that even when the mast flex was relieved the rudder couldn't turn further right than the deformation point. The nicked area is the hamering from aggresively fanning the rudder.

Kosta has now increased the rudder to keel dimension by adding a washer to the lower tail pivot bolt and replaced the hex head anti-servo lever pivot bolt with a dome head bolt.

Thankfully all ended well with a lesson learned that may be applicable to other Dominators.


Dino
Athens, Greece

[dinoa]

another picture

[Timchick]

Good save. Glad it was someone with some experience doing the test flights.

[dragonflyerthom]

good save. Good heads up flying also.

[animal]

is it just me, but does that bolt look like it is not aircraft grade and bent?
Glad you got it down safely.

[edypaul]

My Dom doesn't use a bolt. It uses a pan head screw???

[dinoa]

Animal, it's an 8.8 M6 industrial bolt as are many others on the gyro. AN hardware has to be imported. The shank (grip) length and mechanical specs are similar but of course the quality control not as vigorous. The bend was caused by aggresively whacking the bolt head with the rudder on its long cantilever arm which it wasn't designed for. An AN4 bolt would have bent later because of its slightly larger diameter (6.35mm verses 6mm).

Dino

[animal]

Animal, it's an 8.8 M6 industrial bolt as are many others on the gyro. AN hardware has to be imported. The shank (grip) length and mechanical specs are similar but of course the quality control not as vigorous. The bend was caused by aggresively whacking the bolt head with the rudder on its long cantilever arm which it wasn't designed for. An AN4 bolt would have bent later because of its slightly larger diameter (6.35mm verses 6mm).

Dino
Ok so I am guessing this was a plans built Dom?

so would that grade bolt be the equivalent of a Grade 8 bolt here in the U.S.?

hope you get the bugs worked out, that is a pretty Gyro.

[Aviomania]

Ok so I am guessing this was a plans built Dom?

so would that grade bolt be the equivalent of a Grade 8 bolt here in the U.S.?

hope you get the bugs worked out, that is a pretty Gyro.

8.8 is equivalent to grate 5. the equevalent of grate 8 is 10.9.

[Aviomania]

Dino nice save!! well done!!!

I have talked with Apostolis on the phone couple of weeks earlier. I have a relative wedding in Greece later on this year so i am planning to have few days extra and come and see you guys!!

many happy landings.

[MikeBoyette]

My Dom doesn't use a bolt. It uses a pan head screw???

You are correct. Dad uses a pan head screw for this very reason.

[utahgyrocop]

It is nice to see you did not panic, formulated a plan, and flew the aircraft.

The practice approach and all other preparation prior to landing the aircraft was well discribed and executed.

It saved you and the aircraft.

Great job and thanks for sharing.

Stay safe.

[Uncle Leon]

Congratulations on your excellent in-flight judgement.

And, thanx for the "FREE" lesson for the rest of us.

[Harry_S.]

Good on 'ya, Dino. Superb piloting. ;)


Cheers :)

[helipaddy]

Pan head machine screw, large washer and two large diameter nylon washers.

[Ernie_B]

This is a good example of people (improving ) on an established design, when you build from plans, it is best to follow them ! Also be advised that SS tubing has a very high fatigue rate.
Once you fly it for a few hundred hours, THEN you can make changes that have some background to reference to, or fully understand the PROVEN design!
But to the test pilot, I think your cool head is a great lesson to all!
congrats!!!

[dinoa]

Thanks everyone.

Animal, the gyro was plans built. Ernie supplied seat tank, rotor and head, aluminum, tail, some prerotator parts, rotor tach and pod. The quality of build is excellent as these pictures taken last winter show. Note that the tail outrigger mast attachment shows two bolts that were reduced to one as per plans before the first flight

I just looked at my set of Domi plans bought back in 1994 and I don't see
a specific bolt call out. Someone with more Domi experience or a more astute eye could have seen the hex head bolt shouldn't have been there, but except for this forum and some trips abroad, we are pretty much on our own here.

Nicolas (Aviomania) we eagerly await your arrival. You have wetted our appetite with your innovations and now we need something to chew on.

Ernie B. thanks for the input, Kostas the builder was advised of the limitations of stainless last winter. We have experienced some cracking in the ELA stainless frame that Kostas was trained in and he experienced crack propagation first hand. In the case of the ELA, the manufacturers have been on top of the situation and have provided advance warning and fixes in the form of service bulletins.

Kostas is continuing flight testing after the incident doing short hops and flying the runway but hasn't had it around the pattern yet. Thorough pre and post flights are performed including crack searching in highly stressed weld areas.


Dino
Athens, Greece

[dinoa]

here are some more pics

[GyroRon]

That is alot of machine for a little 503 to push around..... Why not use a 582? And these kinds of problems are likely to crop up when you change the build from what the plans call for, but you know that now

[fiveboy]

.... Recovery from the sink was by moving stick forward, increasing power then left rudder and stick to stay over landable areas.

Thankfully all ended well with a lesson learned that may be applicable to other Dominators.


Dino
Athens, Greece

Dino Congrats on excellent piloting and Aeronautical Decision Making. Im curious about the statement above as it is opposite of what I was taught was the safest way to regain AS.... that is power first, then nose down.

Not criticizing a perfect outcome.... just curious why you did it in that order.

[mark treidel]

Very impressive nose wheel set up. Looks nicely thought out.....and 'beefy'.

[dinoa]

Fiveboy, I think I was taught the same thing but I had height to spare and could have easily recovered without adding power.

The whole flight was executed so that at any time a safe power off landing could have been made.

That's how I fly most of the time anyway, a habit drilled into me from my gliding experience.

Ron you're right. The performance is lacking but Kosta and I weigh about 165lbs besides there were budjet constraints. Even the 503 is used taken off an ASAP Chinook. It's also the reason the machine was plans built and used locally available stainless tube, hardware, wheels, brakes, electricals etc.

Dino

[Doug Riley]

Fiveboy, the "power first, attitude later" mantra was designed to prevent PPO. The idea is that, with a HTL machine, the addition of power pushes the nose down without any stick input. By changing power first, you take this mini-PPO into account before adding even more (i.e. too much) nose-down stick input. You may find that you don't need any stick at all.

A Dominator noses UP when you add power, so the old mantra does not apply to it. I think you get the smoothest results in the Dom if you move both controls at the same time (or use in-flight trim as you change power settings, if you have it).

[Vance]

There are two parts of my preflight that may have helped here.

One is to check for floor obstructions and cycle the rudder by hand with the pedals. The path to the rudder is somewhat convoluted and it is not hard for something to get out of whack. Cycling the rudder by hand allows you to feel anything that is not quite right and make sure the rudder and pedal stops are correctly adjusted.

The second is checking all the controls for full movement once you are in the seat.

Thank you, Vance

[helipaddy]

Dinoa
It looks like one of the best features of the dominator ( once you get used to it!) has been engineered out of Kosta's machine.
It looks like you don't have independent main wheel braking, and the nosewheel is linked to the pedals there appears to be rod ends at the top of the nosewheel strut. Why on earth would you want to change this? The free castoring nosewheel is brilliant in crosswind landings.

[dinoa]

Vance, control freedom in all directions was checked during preflight. The jam occured right after or during the sink probably because the rudder had tilted back into the hex bolt.

Helipaddy, I also made this suggestion to Kosta early on. At first he had the rudder pedals hard linked to the rudder, a set up that might cause him to roll over if the front wheel touched down with rudder applied at speed. Then he installed a spring allowing some degree of front wheel castoring but this resulted in shimmy. The free castoring nosewheel also shimmyed. I guess this gets back to the issue of changing a proven design. At any rate, the nosewheel was hard linked on the test flight. The nosewheel is currently being redesigned the eliminate the shimmy with a spring limited castoring wheel.


Dino

[MikeBoyette]

The plans should include a proven ati-shimmy device. It is bolted to the keel in front of the support tube. It is a pinch clamp that goes around the support tube. To eliminate shimmy it is tightned tight enough to eliminate it but not so tight you can't turn using brakes.

[dinoa]

Thanks Mike,

I was just talking to Kostas about a solution so we'll add friction in the form of the pinch clamp to dampen the shimmy.

Dino

[MikeBoyette]

Dino,
There should be a drawing of the one Dad uses in the plans. I wish I could find a picture of it. Maybe Paddy has one he can post.

[pilotescort]

I love the tall tail as it really eliminates PPO and PIO tendencies. In my case the tail is raised although the pan head screw is still used. Congradulations are indeed in order for such wise thinking on final, and also to the owner for letting experience test fly his machine. Great teamwork.

[pilotescort]

here are some more pics

Just noticed what looks like a double bolt at the mast head for the upper tail mount. Isn't that supposed to be able to "pivot" when the tailwheel contacts the ground?

[Friendly]

Are those coil over shocks for the suspension?. I am glad you and the aircraft are down in one piece. Thanks for the detailed post.

[GyroRon]

To be completely fair, it is NOT fair to even call this gyro a Dominator. It has many significant design changes.

[Timchick]

Just noticed what looks like a double bolt at the mast head for the upper tail mount. Isn't that supposed to be able to "pivot" when the tailwheel contacts the ground?

He stated that they changed it to a single bolt prior to the test flights.

"Note that the tail outrigger mast attachment shows two bolts that were reduced to one as per plans before the first flight"

[helipaddy]

Rons right,
Too many design changes in the wrong direction to call it a Dominator. Looking at the machine, it is easier to fabricate what parts exactly as shown on the plans than what was fabricated on this machine.
Nice looking build though, shame it has engineered out some of the best bits of the Dominator

[dinoa]

How about a naming contest. Winner gets to retest the gyro.

Friendly, they are coil over shocks. Another picture of Kostas shows them better.

Helipaddy or others, can you show or describe in more detail the pan head screw. I'm finishing my Air Command CLT tall tail and want to get the anti servo arm bolt right first time around. I notice from your previous picture that the arm looks like it's in contact with the keel and the underside of the pan head. Also how is the screw secured to the keel?


Thanks,

Dino

[helipaddy]

Yep Ill get you all the photos you want when I'm down at the gyro on sunday. let me know what areas you would like photographed

The arm is not in contact with the keel. there is a large diameter nylon washer between the arm and the keel.

[dinoa]

Thanks Helipaddy,


A better picture of the bolt and if you could a description of the hardware stack from the panhead down to what it's secured to.


Dino

[MikeBoyette]

Rons right,
Too many design changes in the wrong direction to call it a Dominator. Looking at the machine, it is easier to fabricate what parts exactly as shown on the plans than what was fabricated on this machine.
Nice looking build though, shame it has engineered out some of the best bits of the Dominator

One of the biggest is the motor mount. It has the 4130 portion but instead of the aluminum rails that bolt to the bottom of the engine they used a bed mount like Ultralights use.