What happened to Sycamore south of Rhino park ?

[Dish]

[Grumpy]

I am definitely not your BUDDY

Surely this oke is not serious?
Maybe he is, and he's probably 100% correct ? .
He has NO buddies
The mind boggles

[mak]

MODS can we please lock this topic, I think enough has been said.

[nicow]

MODS can we please lock this topic, I think enough has been said.

Why?It's entertaining.....

[Splinter]

No dont lock it, we would like to know the cause of the engine failure.

Regards

[Low Level]

To get the thread back on track.

Ai Jirrietjie tog ouens. Laat ek dan maar die ou nat handoek poepol wees wat op die batteries piepie.

No sweat Johan. Although my handle is Low level, I tend to not fly lower than 150 ft, if I fly low level, and that would be over clear terrain. Very few obstacles - usually other gyros -at that level. I know it is risky, but over hostile terrain, I will stick to a safer altitude. Flying very low level is anyway not relaxing, cause the level of alertness required to fly there, for extended periods of time, is anyway not worth it. It takes the enjoyment and relaxation out of flying.

My name comes from the fact that I am VERY uncomfortable higher than 1000 ft AGL. Joining for Gariep I almost k@kked myself to get to the requested altitude for joining. Old no7 gave me some flack, but . Same for Springs. I will fly around the field and join from the dead side - but joining at 6800 ft - naaah - not gonna happen.

True there are risks involved in chasing a river, or beach LOW LEVEL. I believe in CALCULATED risks for short periods of time. Adrenalien is maar 'n bliksem. I'll then put my safety in my speed.

[Low Level]

No dont lock it, we would like to know the cause of the engine failure.

Glen Meyer at Springs took the engine apart. Quite baffled about the failure. The crown of piston no1 (left back)started burning away, and caused a seizure in the cylinder. Oil, fine water, fine - all info from the engine, airbox temp, pressures fine. No3 ( right back) showed similar signs, but in a very early stage - no damage yet.

A propable explanation might be. When Glen took the cylinder heads off, no.1 and no.4, the topnuts, were loose. The cylinder head bolt nuts could almost be turned by hand. It seems like there might have been air ingress between the cylinder and cylinder head. ( See burn marks on cylinder head skirt). This could have lead to those two cylinders running lean, with resulting detonation. Cylinders no 2 and 4 is perfect, and bolts were still torqued.

When I bought the Sycamore it had an engine cover, part of the body work. About 20 hrs into training the engine had a heat seizure on pistons no1 and no 3. The AMO then, who opened the engine, told me this happens with these gyros with engine covers, because the cylinders are air cooled, unlike the cylinder heads which are water cooled. The two in the rear does not get enough air - with the engine cover - which lead to them running too hot. Although the water temp are within spec, the cylinders overheat, and one does not pick it up.

The two rear cylinders and pistons were then replaced. I never had put the cover back, and she was running well within specs. Just weird that the top bolts came loose after about 150 hrs. Presume it hapenned over a period of time, and that Friday was the final nail.

Any further inputs are welcomed.

Some useless info for the doomsayer(s). I have a mechanical background, and know engines quite well, done a few overalls myself. I therefore treat my engines well. Even two up, I use my turbo rarely. Mostly for take -off, and the odd recover. I watch my temps and boost like a hawk, and will pull back when the temps, on a warm day, are not happy. In cruise airbox pressure will run at, or below, 30 inches. That I will manage diligently.

[THI]

When I bought the Sycamore it had an engine cover, part of the body work. About 20 hrs into training the engine had a heat seizure on pistons no1 and no 3. The AMO then, who opened the engine, told me this happens with these gyros with engine covers, because the cylinders are air cooled, unlike the cylinder heads which are water cooled. The two in the rear does not get enough air - with the engine cover - which lead to them running too hot. Although the water temp are within spec, the cylinders overheat, and one does not pick it up.

Siriaas??

Then I need to remove my covers!!

[weedy]

Hi Leon,

Where the Head Nuts checked again after the last repairs? 10hrs?

[FLYNOTE]

[Low Level]

Siriaas??

Then I need to remove my covers!!

Hi Thinus

I had a discussion with Stefan Grove - owner of Chayair(Sycamore SA) - after the incident. He denied the rumour, and actually claimed better cooling with the engine cover. At that stage I was still pretty green with this flying stuff, and therefore just decided to leave it off. Wasn't in the mood for another engine repair. To be honest, I discussed it with Glen to maybe put it back with some mods. Still haven't decided yet.

Hi Leon,

Where the Head Nuts checked again after the last repairs? 10hrs?

Hi Claude.

No. Didn't know the ins and outs of the Rotax, and wasn't informed my the amo about it. Spoke to some guys who had engines done, and seems none were retorqued, or checked afterwards. In retrospect it is obviously not a bad idea.

[Wagtail]

What you show there and describe is very good signs of Detonation. Our Ozzie mate can take this further, he understand engines better than Rugby...
Loose cylinder head studs on some cylinders will not cause lean mixture under high power, no air will be sucked in during inlet stroke.. The "leakage marks" you will see is actualy from the high temperature combustion gasses leaking out between the cylinder and the head. This causes a drastic disturbance in the combustion front inside the cylinder and this can contribute to higher metal temps. Measure the stud and you will most likely find it a fraction longer than the others...stretch as result of high frequency pulses from detonation. To stay in the air a 914 is continiously running "with Turbo". Even at 27" MAP the turbo is still producing a positive airbox pressure, a MAP of 35" is already a "boost" of well over 7" Hg or 0.5 barg.
Regards

[Low Level]

Hi Johan

The same way we have it. What worries us, is, what was first, chicken or the egg? Did the loose nuts cause the detonation, or the detonation cause the loose nuts?

If it detonated first , why? The interesting thing is, there is no detonation marks in the head, on the plugs or valves.

Dit maak ons dom.

[Condor]

Hi LowLevel.

Spoke to my uncle earlier today and described your situation.

He is a qulified motormac with years of experience on various engines.

Before I could even complete the story he said, over temp and asked if the rings have seized, to which I had to reply yes.

The headbolts will strech causing the loose nuts as described.

He asked me what could cause the overheating, and I dont know.

My 2c worth.

[BONZAI BELL]

Well done Glen
Leon did a good test flight this morning at Springs airfield. we watched the Sycamore flying like never before. Now that the rotor is balanced , we will most likely battle to keep up with Slow level , i mean Low Level