B I G Mac Attack

[Gyro28866]

Well today looks to be the last of the 80 degree plus for a while. My wife wanted to get some pitures of me flying the gyro. So, I told her to meet me out at the airfield and I would fly the gyro, close enough for her to get some really good shots.
She come out and took a few static shots, before I went out to the taxiway, to exicute the takeoff. Mostly a normal takeoff. I flew several circuits close to the terminal area, so she could get some good flying shots. There was about a 20 knot crosswind which mostly lined up to the intersecting taxiway. I decided to get some altitude and give her a verticle decent, so maybe she could get a few frontal shots.
As I lined up about 100 feet past the runway at about 450' agl, and started to slow fly the gyro, the engine lost power, it felt like a coil pack stopped firing; but after about 5 seconds, I realized I was not going to be able to go around and land. So I turned off the master switch and shut the engine down and went for a full on deadstick landing. I exicuted it perfectly and landed on the intersecting taxiway, which is only about 250' long and 400' below me, and I am at the edge of the runway. So, I have got to decend about 400' and land in less than a total of about 350' horizontally from where I am at. I pushed the nose over and went for about 65 mph of airspeed, I did notice that I was actually starting to have a negative groundspeed. This really helped and I was taking advantage of it. At about 50'agl, I started slowing the airspeed and converting it into groundspeed, so I could make the landing on the intersecting taxiway.
Perfect landing, rolled to a stop and had about 150' to spare.
This will most likely finish my flying this year.
I have got to find a 90hp MAC cylinder and piston and ring set.
Hopefully that is all. Here are pictures of the BIG MAC ATTACK!!!
Pic#1: look at cracked cylinder
pic#2: crack down the middle of the exhaust manifold
pic#3: like pic#1 - cracked cylinder - piston showing in crack

[Gyro28866]

Remove the cowling and exhaust manifold
These three pictures shows the head completly seperated fron the cylinder base

[Gyro28866]

More pictures of the seperated head end from the base. The crack went right through the middle of the exhaust port

[Gyro28866]

A few more pictures

[Gyro28866]

The ONLY thing that kept the cylinder head from leaving me, was the cooling tower on top and the exhaust manifold on the bottom being tied together. And I decided to shut the engine down. If the piston had caught the crack - it would have pushed the head overboard!
Hey - look at the bright side --- It did not get my prop, this time.

[Gyro28866]

Upon close inspection, it appears that the crack had an older failed area; and the fresh crack of today.
This leads to think the pre-rotor lower unit failure I had, back in June. might have damaged the cylinder at that time??? Hmmm!


Now, I am suspect of the three remaining cylinders.

Outside of visually inspecting them, How can you detect a crack???

[Timchick]

Ouch. Glad you made a safe landing.

[dabkb2]

WOW, that looks like you have a problem there, more than the obvious. To crack a cylinder like that, something is going on. Was the cylinder re sleeved or ? Are you running 101 LL? I hope to find an answer cause that don't look good.

[Gyro_Kai]

Congratulations on your emergency landing. That looks really terrible, and you did exactly the right thing. Hope it is not too costly to get it fixed.

Kai.

[Rick Whittridge]

David, Those Cly`s in the photos are sleeved. You can tell by the brass plug at the base where it bolts to the case. This is caused by the sleeve being a little to Big on the O.D. & making the Cly casting weak or thin around the sleeve. I have never seen one break thru the exhaust port like that! I have heard of heads popping off!

[All_In]

Glad to here you made a perfect landing in a real engine out!
Way to go!!!!

[Scary Gary]

Good that didn't go through you prop .
Glad all turned out well .

[Gyro28866]

Hey Rick:
Do you know where I can find a 90hp jug???

[dabkb2]

Originally Posted by Rick Whittridge

David, Those Cly`s in the photos are sleeved. You can tell by the brass plug at the base where it bolts to the case. This is caused by the sleeve being a little to Big on the O.D. & making the Cly casting weak or thin around the sleeve. I have never seen one break thru the exhaust port like that! I have heard of heads popping off!

Thanks Rick.

Glad you made it down ok David, that should be an easy fix.

[Gyro28866]

Easy fix, ---- yes
but only if I can find another jug and piston

Rick:
You mentioned the brass plug at the base of the cylinder, I thought it had something to do with the 90 hp jugs, everyone that I have seen, has them.
and It is not present on any of the 72 hp cylinders that I have. Now I know what to look for on a rebuilt/sleeved jug.

dabkb2:
I use 100LL only!!!