Piper Arrow IV catastrophic Cylinder Failure

Sseely

Hi Forum! I posted this on another forum to get the word out….something to think about if you are looking for a CO leak…

Hey Gang-

We have a 1979 Turbo Arrow IV and installed a Aithre CO monitor at the beginning of the year. About 6 weeks ago we started getting small CO readings. My son was flying from home to AUO where he goes to flight school. He diverted into AHN because the CO monitor was reading in the red. Mx worked on the plane, found a few places they needed to tighten up. They pressurized the exhaust and all checked out. He went up and grabbed the plane and got as far as FFC when he had another CO alarm. The plan was to fly to next airport with the gear down (8 miles) so he could leave it at mx & get a ride home. On departure the #4 cylinder head separated from the barrel and had a partial engine failure. He got it back around and safely landed. mx looked at the engine and found the separation. Maintenance said you usually only see that type of failure with an over boost. We downloaded the data from the G3x and it only got to 37.5" on t/o (41" is max). The cylinders were taken off the engine and an engine shop took a good look at the bottom. It got a clean bill of health and we decided to replace all 6 cylinders. The engine has 1035 hrs SMOH but was rebuilt in 1994. We bought it about 1.5 years ago and flew almost 380 hrs last year. I asked shop to take a look at the exhaust again and told them about the CO issue. On the test flight and subsequent flights we have had readings of zero on the monitor. We are thinking there was a crack in the barrel and that is what was giving us CO readings and it finally let go with the cylinder failing. We change the oil every 25 hrs. and do a compression check and boroscope. Something to think about when chasing CO leaks and can't find. There is an AD on Continental barrels and a procedure to pressurize with piston at the bottom of the cylinder and check for leaks...Food for thought....

Scott Sherer

I'm glad everything worked out okay. :)

empannin

Wow - that is finding out the hard way. Thanks for the tips. Good learning to also have maint check the barrels. Often you can test these by sound as the fins will have a dead sound when plucked in the area of the crack.

You might also want to carefully check timing but I don't think this is user error. A note on the TIO-360's - they also have a blow off valve in case the MP exceeds limits. If you are replacing with new cylinders I would see if you can sell the old ones. I bet they could be overhauled and there is a shortage of cylinders overall worldwide.

Good reminder on checking compressions with the piston at the bottom - I have never seen a shop do it but I have done it on occasion. It is not for recording compressions but designed for detecting a cylinder crack. In a normal compression check the piston is at the highest point, the rings seal off close to the plugs and any problems with the cylinder that are not rings, valves or the spark plug area are missed.

Sseely

Eric-

Great points!! We have a Merlyn Waste-gate on the engine but it can still provide a boost over 41"

The CSB from Continental is CSB 14-1A. Even though our cylinders were not in the listing, it has the procedure to check for cracks...

empannin

SSeely, in the TSIO-360's there is also a blow off valve in the induction system that is supposed to open up if the pressure exceeds XX MP. I think it is set up for around 42" but of course you are not supposed to count on this.

The Merlyn system has this too.

ATN & XRIS

Hello everybody,

It has been a while since I participated to the forum - sorry for that.

I had almost the same issue with my conti.

I own a 1978 T-Arrow since 2018 with 2900 hours TT and about 400 hrs since purchase. In 2019, -tThe aircraft had a bare metal re-paint, new interior and some Avx upgrade (Two G5, GFC 500 3 axis, EDM 900, GTX335, GMA345 and GTN650).

In Sep last year, During the takeoff roll I had a loud bang, retard the throttle, vacate the runway, park in front of the tower and shut down asap. I lost about one quart of oil in about 30 seconds.. One of the cylinder had separated from the body. Like Seely, the last rebuild had occured in 1994 but my engine had 1400 Hrs since then.

Now, I'm facing another issues because I sent the TSIO to an engine shop for a complete OVH (Prop & governor aswell). They performed an NDI and found a crack on the crankshaft.

The problem now is to get a crankshaft. The shop ordered a new crankshaft in Nov 2021 by Continental which are unable to provide a delivery date. My engine shop has all the required items to proceed with the OVH but the crankshaft...

To be continued...

PS: the crack most probably occured in a prop strike before I bought the aircraft (when ? how ? no clue). I was unaware of this occurance (no entry in the doc history)...

ATN & Xris

empannin

Good call to abort and if it had to happen it happened at the best phase of flight (pre-takeoff).

That sucks on the crank delay. Are there any used cranks that would meet overhaul requirements. You could probably buy a used one, take eventual delivery of the new one and then sell it at a premium

ATN & XRIS

Hello Empannin,

Impossible to find, even a used one... The engine shop is also looking for it while keeping the order "alive" by Continental.

empannin

ATN, sorry. Insane how thin the supply chain is for key parts. For the local shops to me this is a disaster as they are running out of space to stuff planes waiting on parts. Some are ok on the ramp but others need a hanger. They are even making "hanger calls" now as this is more efficient vs shifting planes around all day. There is a prop strike experimental that is close to 1 year now waiting on an engine (also delayed due to insurance, etc). A tail dragger that taxied into the plane in front of them.

Seneca38173

Hi ATN,

Saw your Zyglo inspection pictures, and am curious about a couple of things.

Have you talked with the Production Scheduler at Continental Motors? The new factory, and especially the new owners, are heavily invested in digital manufacturing, and they know exactly when your crankshaft blank will arrive from the forge, when it goes to CNC, to hardening, to QC, etc. You should be able to get that person on the phone and get the straight story about what to expect. They should be proud to brag about how well they have their process under control, especially to the Customer for a 15K crankshaft.

Has your existing crank been inspected by any means other than Zyglo? In order to certify a hardened crank, and reassemble the engine, it must past an Ultrasound inspection as well, performed by a certified NDT inspector. Curiously enough, the couple of specialty shops I know with the US inspection capability also have the expertise to fix quite a few crankshaft flaws, and yours may be among those they can fix.

Good luck, and keep us all updated,

Bob

ATN & XRIS

Hello plane lovers,

Thanks for the replies & tips, I will check it out by mail to Conti.

On the other hand, the engine shop told me that my TSIO is still a F version. I suppose that they want to upgrade to FB with a beefier crankshaft. This also means that, the shop that OVH the engine in 1994 didn't upgrade it...

That's part of the "mist" related to EASA (JAR in the 90's).

I'm a former Belgian Air Force pilot, retired in France, owning a Belgian CPL and flying a Germany registered aircraft, now maintained by a French CAMO reporting to a German one...

The engine is at a Belgian shop (PMM Wing service).

I'll keep you guys posted once I receive more informations.

Take care.

ATN

Scott Sherer

Thanks ATN for your post above. Good luck and tell us how it all comes out.