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Partial power loss

Pilot_DAR wrote:

Yes, the engine might not have taken them anywhere other than to the forced landing, but the dying part was because they did not continue to control the plane and maintain flying speed, not because the engine was not developing power.

Exactly. Reading accident reports, the wording in those circumstances are something like: “The cause of the accident was – the pilot’s inability to maintain flying speed when the engine stop producing power”.


Agreed, LeSving and Pilot_DAR, but it also points out that things go wrong when a pilot thinks he can chance it, rather than committing to engine failure drill regardless of partial power or not. Control is obviously paramount in any situation, as you say, but in the twilight zone of indecision (“will I make it, won’t I?”) distraction takes over and things can, and do, go horribly wrong.

This is the crux of the report imho.

North Weald, United Kingdom

jgmusic wrote:

rather than committing to engine failure drill regardless of partial power or not.

Decades back, in my trusty C 150, I took off a nice grass runway, which ended at a large lake, As I crossed the shoreline toward the water, it began to run really rough. A turnback was certainly out of the question. An engine failure drill would have been to prepare for ditching – but, it was still running, poorly, but running. I lowered the nose, maintained a safe flying speed, and very slowly climbed away, circling back toward the runway. As I did, the exhaust valve unstuck, and full power was available. Being cautious, I circled up for several minutes, with the runway in a good gliding position. The engine continued to run well, so I flew back to the airport (it was mostly fields on the way there anyway) where engine work was easily accomplished.

Thus, by not jumping to the conclusion that a ditching would be required on the chance of a complete engine failure, I landed the aircraft safely at a suitable airport – why ditch a pretty good plane, just ‘cause it’s running rough? An airplane engine to some degree is actually four or six engines, with a common case, crankshaft, camshaft, induction, and somewhat ignition. One of those four or six part engines can go wrong, and the others may not be at all affected – if it can be safely done, keep flying the plane, with suitable forced landing areas always in your mind. You may prevent being asked the question I have asked a few times – Why’d you land it here, rather than flying it home? It was still running!

Home runway, in central Ontario, Canada

Pilot_DAR wrote:

why ditch a pretty good plane, just ‘cause it’s running rough?

True, and surely an exception to the proposed wisdom

A great story but maybe you also had luck on your side? I think the report is just trying to encourage pilots to assume the worst, as a default position, rather than cling on to a hope that could result (and has, statistically) in disaster. If you manage to wing it, great, but prepare for the fact that you might not, like the highly experienced Mustang pilot in the video.

It’s advice I’ll follow anyway.

North Weald, United Kingdom

jgmusic wrote:

If you manage to wing it, great, but prepare for the fact that you might not,

Very much so. I’ve had six or seven events of power loss, where I flew the aircraft with great caution to an airport of maintenance. I’ve had four forced landings. In two of those cases, the engine was running, but at idle only, so of no use for flight. Yes, luck has been on my side, I have never damaged a plane I was landing, and each forced landing was to a place from which a safe takeoff was later possible. Other people I have known did not fair so well. Too quick to make a decision, where with a few second’s thought, and somewhat different action, things might have worked out much better.

Home runway, in central Ontario, Canada

I should mention that Pilot-DAR is a specialist in aircraft certification and design and flight testing of various aerodynamic modifications.

Shoreham EGKA, United Kingdom

I had a partial power loss (unable to maintain altitude) and I’m still not sure whether I did the right thing in bringing it back to the airport. Yes, it probably saved the plane as the wilds of mid Wales are not a good place for a forced landing, and it probably saved me bumping my head as Turbs tend to flip on rough ground.

On the other hand I wasn’t sure I would make the airport until a few minutes before landing. Half-way between the problem starting (6000ft) and the airport I would have been at 3000 feet with a reasonable choice of big fields, compared to my options at about 1500 feet when I was finally sure that I would make it even if my engine gave up completely. I think you could make a strong argument that I might have been safer to have made a forced/precautionary landing when I had 3000 feet rather than trying to make it back to the airport which left me with progressively fewer options.

Last Edited by kwlf at 18 Aug 20:30

kwlf wrote:

On the other hand I wasn’t sure I would make the airport until a few minutes before landing

IMO the result justifies the solution in a way. When the result is that you live to fly another day, and you do it without a scratch, then you cannot possibly have done all that much wrong. What often happens (according to accident reports) is people forget to fly the aircraft, forget to maintain speed, they stall and flick and the result is given. If you don’t do that, then your chances have increased from zero to a whole lot.


I was breaking in a new engine in a C 206 years ago. It was a perfect day, and I went sightseeing, knowing I had to fly it for a few hours. Mistake, I should have stayed near home. The only thing I did right was going way up high. 40 mile from home, and out over a beautiful lake, oil streamed onto the windshield. The engine was running fine, and Ts & Ps fine, but I did not want to run a brand new engine out of oil, so I pulled the power to idle, and pointed to home. I had many suitable fields along the route to home, but I really did not want to have the boss doing an engine change in someone’s field, when he owned a perfectly equipped hangar I’d flown too far from! I let the engine idle, keeping a very close eye on Ts & Ps, and glided. With the help of a nice tailwind (and having been at 13,000 feet), I glided right into the downwind at the home airport. I glided the circuit, and only had to add a burp of power to roll onto the paved apron. The boss had seen (though not heard) me coming, and came out to see what the problem was. It turned out it was only the oil cap not on properly (also my fault for not checking), so aside from a well lubricated, plane, no harm done. After my several mistakes, I made a few good decisions, watched my progress carefully, and made it home with no risk nor fuss.

Home runway, in central Ontario, Canada

IMO the result justifies the solution in a way.

Perhaps in a way it does. It implies that it wasn’t a completely stupid thing to do, because if it were then I probably would not have made it back to the airport. I’m glad I did what I did, because it turned out well.

However what one needs to do is to imagine having the same issue again multiple times. When I started my approach I had about 500 feet in excess which meant that I probably could not have made the runway had it been a mile or two further away. Perhaps if I reran the scanario ten times I would have only made the runway five times; I like to think I could make a survivable forced landing into a largeish flattish field most times. What proportion of the time would I have made a good landing into a field chosen at the moment I realised I wasn’t going to make the runway at perhaps 1000 feet?

The answers depend very much on whether you’re considering what might happen in the plains of Southern England or the wilds of Scotland or Wales where it can be hard to find a good landing place.

Last Edited by kwlf at 19 Aug 18:40
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