The difference between 2500 and 2700 is roughly 25% extra power being potentially absorbed by the propeller. Given a lot goes into parasitic drag, this translates to maybe a 1.5x to 2x extra rate of climb.
That is something anyone familiar with the type would notice right away.
So either it wasn’t noticed, or it was noticed and was accepted as normal. Either way, the pilot thought it would be ok for the visible obstacle clearance.
I wonder how old and tired that TB10 engine was….
WhiskeyPapa wrote:
I wonder how old and tired that TB10 engine was….
Could be? Does it matter?
I think many (including myself) find that old school C172 do get stuck at 5000ft on summer, so they will blame it on engine, airframe, technique
6 months later the same aircraft go up to 12000ft, but honestly it is not that bad to blame density altitude effect on weak engines, at least you know you have to do
The way I view now it does not matter if it is density altitude, tired engine or my poor technique
What matters is: I get 100fpm not 500fpm, so not my lucky day in hills/mountains
Not a mountain flyer but the next time I go to try, I will make sure to climb 2000ft above nearby peaks before doing any valleys (my dry run of the day)
An engine which is “worn out” still develops close to rated power. Only if the valve train is in a really bad state does this start to fall off. Some previous discussion on this topic. One accident engine was found to have valve travel reduced by about 5mm yet the power was just 10% down. Issues are in fact more visible at idle, because the gases have time to escape etc. That is when you spot camshaft damage, sticky valves, etc.
However an accident report would normally highlight this; even if they cannot run the engine they will open it up and comment.
Another thing is that a pilot who is aware of the book performance will look out for whether this is being achieved. For example I expect to see +1000fpm at sea level, give or take a bit. But if I was getting just 500 then something is obviously wrong.
There was an accident report a few years ago local copy which now is often cited when discussing how an abused engine will still develop normal power. This particular engine had been installed in 1983 after an overhaul and in operation until 1997 when the aircraft went out of service for 13 years. There was no sign the engine was prepared for long term storage. In 2010 the airplane got bought and put back in service after both magnetos and the carburettor were overhauled. Corrosion was found in the cylinders in a boroscope inspection, yet the engine provided good compression values (72-75/80) and performed to full power on a test stand. They also found that the engine had been run with automotive fuel despite the fact that there was no STC.
The one I had in mind was this PA28 G-AVRP from the Isle of Wight. It’s a very good read.
It‘s a good (and natural) thing that different people learn different things from such an accident – we are all individuals and prone to different mistakes we make ourself and the best we can do with such tragic accidents is trying to avoid our own mistakes.
In this case (like always) imho it is important to see that it is not „one single mistake“ that led to this accident (like e.g. reducing RPM to 2500 instead of full) but a chain of a couple of significant mistakes that altogether caused this sad outcome, like:
- the not proven but probable reduction of RPM in climb
- the failure of the pilot to notice that actual climb performance was significantly below handbook values at all phases of the flight
- a chosen airspeed that was significantly above Vx at all phases of the flight
- a chosen flightpath across the ridge (at almost 90 deg) that is unsuitable for mountain flying at the edge of the performance envelope
- maintaining a pitch attitude that prevented him from visually checking terrain clearance at the critical phase of the flight
For a flight that according to the accident report would have given him only 300m of terrain clearance at handbook performance values (which are measured at optimal flight technique and tactics), this was unfortunately one mistake too many.
We all do a couple of such mistakes on every single flight – let‘s knock on wood that for us they never pile up this way in a single flight.
Aren’t tb10 equipped with a VP? You are all talking about prop speed but I’m currently flying 2 tb10 and they are all equipped with VP. And I’m putting ft until 1000 agl. Poh then mentioned full throttle for climb.
A sad story anyway, as you said. I would say each experience is a by-plane one. Even the 2 tb10 are not equal, one has a 3p prop and the other has 2; I would guess that the 3p one would have a better climb an cruise performance, but it seems it’s engine is giving less power, and stall warner is 5knot higher…
greg_mp wrote:
Aren’t tb10 equipped with a VP?
Yes, they are. So — ignoring second order effects — the power at 2500 rpm and WOT should be about 92% of the power at 2700 rpm.
From here
Malibuflyer wrote:
Hasn’t there been another accident report recently where a pilot who also had high hours with most of them in jets crashed while trying to pass a ridge but it turned out that the climb performance of his SEP was just few 100 feet short of the ridge?
That crash, incidentally, was on the exact same day the Ju 52 crashed.
