Is your plane trying to tell you that something is about to break?

Mike Busch says almost the same. When oil pressure varies for no reason, check the main bearings.
On Vans forum, a guy took had to jump start with a dead battery, then had a total electrical failure in flight.
In many accident reports, you feel the end coming from the beginning

Popping sound from exhaust on the 3 previous flights should have told me something was about to fail, which it did at 5000ft over the English channel
A36 Bonanza @ 1700 hours and 20 years old (IO550B)
I put this pic up here a few years ago, it may save somebody’s life

I think anything the aircraft is telling you should be investigated. The best indications are usually knowing all the parameters of your aircraft and recognising when anything is outside those paramters. The most challenging are intermittent faults. One that comes to mind for me was an intermittent engine miss, it was quite sublte, but had never been present before. The engineers found nothing on a few occasions. Anyway caution prevailed and we pulled the whole injection system which went off to the States for overhaul. The engineer reckoned we were lucky the engine hadnt already suffered an in flight failure. Seems to me 9 times out of ten most things mechanical will tell you something is about to fail before it does. Ignore the warnings at your peril, until you are absolutely certain what the cause is.

I think you have a zero zero tolerance, and this has to be correct. The reality is usually leaving something ends up costing far more, so even trying to economise doesnt make sense, I am afraid if something needs checking get it done!

If I were an owner and knew my own aircraft through and through, I would spot problems earlier and easier, I guess. As a renter, flying a variety of aircraft, I don’t always know wheter something is an oddity normal to that specific aircraft or wheter it is an early indication for something going wrong.

Last winter, I wanted to fly in the Aquila A210 with the FI who is also the owner of the aircraft. He mentioned something about the battery being low on power. When I started as per the checklist, with Strobes ON before ignition, the battery died and we had to cancel the flight :(

If your oil gauges are electrical, the first thing I’d investigate is the electrical connections.
All my pressure/temperature fluctuations have, forty and cheaply, been that.
And not just in the obvious places. A loose starter motor connection didn’t show on starting, but when it cooled down the oil pressure and temperature went up.
A “starter engaged” warning light wire had not been reconnected, but left taped up. Much later, it came loose. As it flapped about, each time it earthed the oil pressure dropped.
Over the years, my video camera showed an increase in vibration, requiring improved mounting.

Fuji_Abound wrote:

Anyway caution prevailed and we pulled the whole injection system which went off to the States for overhaul. The engineer reckoned we were lucky the engine hadnt already suffered an in flight failure.

Did you get any more detail on what was wrong with it, or were they just rewarding and reinforcing your decision to send them some business? ;-)

Had several, some in rented aircraft and twice in mine.

1. Rented Partenavia P.68-B
My family arrived for a visit and we flew to the Isle of Wight. Every time when I have leaned the mixture the aircraft started to roll to the right, in order to fly S&L the right engine had to be about 2gl/h richer. On return it was reported to the club owner just to be dismissed with “Why always you?”
A week or so later the aircraft went for an annual, I dropped in told the engineer the story and asked if they found something wrong with the engine, he looked at me with big eyes and said that the top of the engine found to be dyed blue. One of the injector lines was cracked and sprayed on the engine, this lost fuel manifested itself as lost engine power, in order to equalize the engines power there was a need to inject more fuel.

2. Same aircraft
Flew to Antwerp, as T/O was early’sh morning the aircraft was refueled the night before by the club owner. On the way I have noticed that the aircraft was flying (left) wing heavy, also, on one engine X (I think EGT) read incorrectly and on the other Y (either RPM or F.F) was also reading incorrectly so I had to balance the engines by feel and sound. All was good and it was time to fly back home. Fuel calculations showed that all is well and that there is enough fuel in the tanks but I had this sort of feeling that something is not right and decided to refuel. One wing took more than X2 of the fuel that went into the other wing, calculations showed that if I would have not refueled, one engine would have quit mid channel. Several years later a privately owned P68-B (I think it was based in Denham) crashed and some people were killed. The AAIB report found that when the P68 is parked with one wing lower than the other (i.e. on a slope) the fuel selectors allow fuel to cross from one wing to the other even if in the OFF position. The aircraft that I flew was parked that way all night allowing the fuel to leak through the vents.

3. Rented Archer PA28-160
There were popping coming from the engine every time I tried to lean the mixture, was ok at full rich. Exhaust pipe found to be with a hole. Also the aircraft felt unstable during taxi. At destination I have lifted the nose and found one of the nose wheel plugs broken which allowed the bolt to move from side to side and the wheel to wobble. The only thing that prevented the wheel from falling off the aircraft was the spat that held the bolt place.

4. My own aircraft PA24
Noticed oil consumption of 3.5 quarts after 3h flight, normal consumption was ~ 1q. per 5.5h. Refilled flew and had the same results. Filter was opened and metal was found. Lycoming procedure was followed and then the engine was sent to be O/H. The front crankshaft sleeve’s pin got broken and started to cut into the case. 50h after the O/H the engine started to sound like a machine gun, when it was opened we found damaged camshaft, worn rings, scratched cylinders and the double gear (the one that drives the camshaft and the left magneto) sheered a tooth of the camshaft’s gear. Somehow the engine kept on turning and the aircraft kept on flying.

Graham wrote:

Fuji_Abound wrote: Anyway caution prevailed and we pulled the whole injection system which went off to the States for overhaul. The engineer reckoned we were lucky the engine hadnt already suffered an in flight failure.

Did you get any more detail on what was wrong with it, or were they just rewarding and reinforcing your decision to send them some business? ;-)

I did. I am afraid I cant recall the full technical detail but essentially the diaphragm in the injector has split or perished. I am afraid I cant recall why it prevailed as an intermittent cut.

I dont think it was just business for a number of reasons. The engine was perfect after. The engineer who actually took it apart chatted to me on the phone. He was a lovely old timer and I felt could be entirely trusted (I know the best con. atrists and all that). The unit was returned with the defective parts.

As I say it was a while ago and I wish I could recount the exact technical details.

Another story was the prop govenor. I have always been in the habit of checking the take off performance against a known point on the runway on any of the aircraft I have flown. It was noticeable on this occasion over a period of time the performance had progressively got worse. Discussion with the engineers lead them to suspect the govenor which was duly removed, sent away for overhaul and refitted. The fun part of the story is I had asked the engineer who I knew well to fly with me on a few occasions after annuals etc. For one reason or another he hadnt. On this occasion he agreed. We stuggled into the air. I possibly should have followed my own rules and aborted, but it was a long runway for the aircraft. We barely climbed away, and the engineer agreed with me an early and immediate return was the best course. Embarassingly it turned out the overhauled governor had not been properly calibrated (although this was part of the overhaul), and perhaps, should have been strobe checked after refitting. It was duly calibrated and the performance returned and was, I seem to recall, even more sprightly.

Unfortuantely there are a few more stories all of which point to the value of knowing all the performance parameters of your aircraft.