REENO Aviation Flying Club

Sorry for the long delay in making a new post. It took me a while to get to write about this topic. We had to make sure all was settled with insurance and repairs. The plane is flying again and doing well.

Short story about this particular failure. A few hours after maintenance to help fix an oil leak and inspection of a cylinder, in stable cruise flight at 12,000 ft the engine suddenly started running super rough. It was quickly followed by a loud noise, and the engine was quickly secured and feathered. A stable emergency decent was initiated and an uneventful landing followed at an airport with a really long and wide runway. The damage was thankfully limited to a decent sized hole in the cowling, and a ruined engine. The connecting rod to one of the cylinders had fractured and had exited the airplane through the case, leaving a giant hole and a bunch of ground up engine parts floating in the oil. The oil had not escaped much, and on ground inspection all 10 quarts were still in the case. Apart from a very long ride home facilitated by one of those super kind people one meets at FBOs all over the country, the damage was very limited. The benefits of a twin engine airplane and a seasoned pilot resulted in an optimal outcome of a catastrophic engine failure event. The only thing very hurt was our wallet.

Engine failures are uncommon. We prepare for it all the time, and we learn during out PPL training in single engine planes to always be on the lookout for a place to land. We stay afloat in the air by the willing grace of our 4 to 6 cylinder bangers in front of the fire wall. We can’t acknowledge the failure risk too much, for we would not take off. The reality of sage advice such as “fly it all the way to the crash” and the departure briefings that are thankfully becoming more and more common in General Aviation, is that we stow away these pieces of knowledge thinking (and hoping) this will never happen to us.

So how common are engine failures? That depends a bit on the definition of an engine failure. If we start from a position of “engine stops producing power”, we have to concede that most engine failures are happening as a result of an empty tank of avgas. Most of those empty tanks are the result of pilot error. Some empty tanks, and some situations where fuel can’t reach the engine certainly do have a mechanical basis. The type of engine failure that I am most interested in is the mechanic failure of actual engine parts coming apart. Cylinder failures, crank shaft fractures, or such as in our Baron described above, a connecting rod blowing open the entire case. It is remarkably difficult to find an accurate number of these kind of failures. The McFadden report gives some indication, and there are sparse reports from engine manufacurers. The ATSB’s 2014 investigation into failure rates in piston engine powerplants showed that the traditional Continental and Textron/Lycoming engines had a failure rate of about 13 failures per 100,000 flight hours, with Rotax coming in at a slightly higher 15 per 100,000 flight hours. 

I think that perhaps these data are not perfectly representative of the total number of engines giving the ghost due to failure. If you end up landing with one football sized hole in the engine, but you make it to the field just fine, nobody the wiser. In fact, one of the most frustrating aspects of the whole ordeal above was the collective “shrug” of all the shoulders of people that we connected with related to this incident. The insurance does not pay for it, only reimbursing damage to the airframe. The FAA followed up on the emergency for “statistical” purposes, but just congratulated the pilot for his excellent handling of the emergency. The engine shop and mechanics rightfully, but still very unsatisfactorily, glanced into the engine and its ground up metal parts and concluded that there was not much to be learned from that heap of misery. Pursuing shops, manufacturers and mechanics legally would add to the already high cost of repair. It would likely not result into the one thing that we would really want. And no that is not money, but an explanation as to what we can do, inspect, or replace to avoid this from happening again. As stated before, the whole premise of flying hangs on the trust one places in self and airplane. And a failing engine is not helping that trust relationship.

So we know it is rare, but not so rare that it does not happen. I can only recount my own experience with engine failures, and relate those to you. I have had three major engine issues in my 15 years or so of flying. In talking to my fellow pilots, that is a bit higher than average. The failures were not all catastrophic, and the failures I am reporting I did not all fly the emergency. The first one I was flying. My first solo cross country flight out of KEQY, on my way to KFAY. Cruising at 5500 and with the experience of a one-day-fly, i felt I did it all correctly. Slightly leaned out, all looked great. I clearly had GAS, gas/fuel, air and sparks. The carburated engine of the flight school Cessna was maybe old and beat up, but it was doing just fine. Until, out of the blue and over the middle of no-where, the engine just died. No shakes, no trembles, no sputters, it just died. Windmilling prop. I looked around, took a deep breath, and stated to myself: “I guess this is really happening”. I pitched for best glide, which remarkably took a while to get to. The plane didn’t immediately slow down. I was still flying, just in silence. I pulled the check list, and verified I did all the emergency steps. Moved all the things I could move, and watched the altimeter go through 3000 ft. I pumped the mixture knob last and stopped my attempts at re-starting. I focused outside and aimed for one of the many fields around. I ran the check list and right when I was thinking about whether to pop open a door and perhaps cut off fuel, the engine suddenly started running again.

I climbed back up to 5500 and landed uneventfully, but somewhat shook up, in KFAY. They could not have been nicer there. I called my instructor, and found a mechanic. Here I made the biggest mistake of my entire flying career. My instructor was convinced it was something I had done wrong. He questioned my fuel, my leaning strategy, my competence and everything else. He suggested I go talk to a local mechanic. This young man, who I thought was probably a mechanic, looked at me funny and suggested I do a run-up. I did for 15 minutes or so. I then decided to go to my next point of intended landing, and took off from KFAY to complete my three-pointed cross country tour towards my rating. I figured all the “authority figures’ around me must be right, and also that if I did not have the gonadal fortitude to get back in the plane I might as well have quit on the spot.

It happened again the next day. My instructor and another student deadstick landed the plane out of the pattern onto the runway. The engine was not running anymore and was opened. Lead balls were everywhere. Several valves were stuck and the ignition was shot. That’s why you ground lean, folks! To prevent that.

A second engine failure happened in my Bonanza. I was not flying this emergency. Over the mountains, in IMC, the engine started suddenly running super rough. lost half the cylinders as could be seen on the engine monitor. The plane was expertly handled and glided on half power in the direction of Tri-cities, in the clouds, but broke out and was diverted to Elizabethton and landed thankfully without further issue. A field mechanic diagnosed a super rare intake valve fracture. This is not supposed to happen. The piece of metal was the size of a silver dollar and perfectly trapezoid in shape. It was missing, and although in hindsight found to be impossible, thought to have departed the plane through the exhaust. A new cylinder was installed, and the engine thoroughly bore-scoped. I picked up the plane, and flew it back home over the mountains without any problems. On the very next take off from KINT, the engine did fine, I turned left towards Charlotte, and at 8000 ft after leaning in cruise, it started running rough. I declared an emergency and while under power, returned to Winston. The engine ran fine after i had pushed all handles to the firewall to get home through out the return and decent. Again met with seasoned mechanics, I was skeptical of the explanation that this was ‘cavitation’ during rapid climb out on a 95 degree day, but I acquiesced.

On the next take off, the engine sputtered after rotation, and while explaining to my daughter that ‘everything was fine, but I just wanted this checked out’ I pulled around the pattern quickly and landed. I refused to fly that plane until it was explained to me why it did that. Well, after some more thorough inspection, a giant explosion hole was noted in the cross-over tube, and cloinking around in the tube was the big piece of intake valve that had never actually left the airplane in the first place… This was all repaired, and all was good since then.

The last failure was one of my flights again. Weird one again. But this time I was no longer going to be convinced by half explanations. The twin-engine Baron intermittently had a dramatic loss of fuel flow to one of the engines. this would happen inexplicably in cruise. We watched this once, and we boosted the electric fuel pump, which solved the issue. Turning the pump back off, and all was ok. Until the next flight when it did this on take-off. Twin fliers understand that this can be pretty critical. Thankfully, in a two pilot operation, we had briefed this situation, and as the pilot flying I focused on airspeed and directional control. We both had the same idea immediately, based on the briefing, and the boost pump came on, solving the problem. It is eye opening, the yawing of a slow Baron with one engine losing thrust… and it is quite the Bronco when that power explodes back into life. Anyway, the plane was returned to the shop. The entire fuel system was checked and all was ok. Up to the point that we decided to inspect the one thing that clearly was working fine: the electric boost pump. When blowing on the fuel pump, it seemed obstructed a bit. It was dismantled and surely, one of the plastic pump fins was fractured and covered the fuel flow opening perfectly with the pump not running. Turning it on pushed it away from the opening. How’s that for trouble shooting?!

These stories serve some lessons perhaps, but also underline that understanding your engine, your fuel systems, and the way it all works together can save your bacon one day. I emphasize that experience has to grow, and that I certainly learned not to accept illogical explanations for critical events ever again. The narratives can further hopefully help you to be prepared, and be a bit more prepared than you were before. These engines are supposed to run for 2000 hrs at least. But they may not, despite our best efforts to keep them running optimally. Stay cool and collected and plan for these things ahead of time. Departure briefings seem silly sometimes, when doing them every time, but maybe not that one time you need it. Digging through your PoH and asking / reading / learning how it all actually works is important. Talking to your mechanics, helping out, looking into engines, may give you a better sense of why and how. Most importantly, speak up when something is abnormal.

I think serious engine trouble happens at least 10x more often than reported. Thankfully, most events result in little more than damage to your wallet. Build a trust relationship with your plane, your mechanic, your team. Trust, but verify. Accept risk, accept that it can happen and don’t allow yourself to be fatalistic about it. Stay engaged with the issue and solve it. Lean out, and i mean not the mixture, but yourself. Think. G-A-S. it is all that is needed for combustion. I am happy to talk about this some more. Just ask.