Magic numbers

[Lone_Ranger]

Engine/Airframe at 247hrs.


I see this sort of thing now and again......why?, nobody actually looking to buy an aircraft will swallow this, in fact its likely to make you disbelieve everything else in the advert....people are strange

[Cusco]

With your lack of trust you will miss out on many aviation bargains.

[Lone_Ranger]

So you know the magic method of making flying hours equal engine running hours?, enlightenment is requested .......oh one what he said

[Pirke]

If it's from 2006 to 2013 then 247 hours could be realistic.

[Mach Jump]

So you know the magic method of making flying hours equal engine running hours?, enlightenment is requested ...

Both engine and airframe hours are counted from T/O to Ldg, so why wouldn't they be the same, on an aircraft before it's first engine o/haul?


MJ:ok:

[Genghis the Engineer]

Both engine and airframe hours are counted from T/O to Ldg, so why wouldn't they be the same, on an aircraft before it's first engine o/haul?


MJ:ok:

Really? Certainly Rotax engines generally count running time - which seems fair enough to me - the wing may only be under load from take-off to landing, but the engine is doing useful work for rather longer.

G

[Mark 1]

I believe Mach Jump is correct.

Schedule 6 of the ANO requires that you record time from take-off to landing for both airframe and engine (& propeller) log books.

Rotax may have an additional manufacturer's requirement based on actual running time, but log book times for engine and airframe are just airborne hours.

[150 Driver]

I believe the running time is a specific Rotax (and possibly other) requirement, the instructions that I have always followed on non-Rotax engines is take-off to landing.

Seems odd as common sense says the point made above is right - even if taxying the engine is under load - but no point in artificially bringing forward an overhaul if not legally required.

[Pirke]

During t/o and flight the engine load is much higher than during taxi...

[ChickenHouse]

(Engine/Fuselage 247h) tells you that it well passed the most dangerous first 100h, the engine was not undergoing OH yet and was not separated from frame. If you have a Cirrus with 15.000h lifetime frame, or even a 172 Cessna with 30.000h lifetime, it does not really matter, or? You could pennypick on hobbs hours, flight hours, block time, running time (became relevant since these nasty new TBR instead of TBO engines came into play) or whatsoever - it is always only an estimate for wear.

[dont overfil]

On the aircraft I used to fly we noted both the hobbs (records with electrics and oil pressure) and the tacho.

Tacho was 16% lower. However the aircraft did have a wobbly prop.

D.O.

[abgd]

Isn't the TBO for turbine engines judged partly on cycles - i.e. takeoffs and landings. The reasoning presumably being that a period at 100% power counts for more wear and tear than the same period in the cruise.

Likewise, you could argue that taxiing for long periods is bad for plugs so you should be doing 50 hour checks more often.

It seems to me that ideally in this day and age we'd have better means of judging the TBO than mere hours flown. e.g. as someone who rents by the hour it's in my interest (short of engine failure) to choose a high cruising speed and thrash the engine and burn more fuel because it's cheaper for me that way. For an owner it would be considerably cheaper to fly a bit slower, be kinder to the engine and get more flying for the same fuel.

[onetrack]

There was a fatal accident involving an Aero Commander 500S here in West Oz in 1986, whereby the engines were run up for a number of hours, by an engineer, as part of ground testing for onboard survey equipment.

Those testing hours were not recorded, as only flight time was required to be recorded.
The PIC had previously fully-fuelled the aircraft without taking it out. Upon returning to it, he presumed it was still full of motion lotion, as no flying time had been recorded.

The fuel gauges were inoperative, and he failed to physically check the quantity of fuel in the tanks.
He took off and ran out of motion lotion a short time thereafter, resulting in a crash into heavily timbered terrain, with resulting fatalities and total destruction of the aircraft.

Investigation: 198600131 - Aero Commander 500S, 2km North of Canning Dam WA, 27 February 1986 (http://www.atsb.gov.au/publications/investigation_reports/1986/aair/aair198600131.aspx)

This would be an example of engine hours and airframe hours being out of sync after a lengthy period of operation, where ground testing with engine running is incurred.

[foxmoth]

This would be an example of engine hours and airframe hours being out of sync after a lengthy period of operation, where ground testing with engine running is incurred.

Actually if they were in sync before they would still be in sync after precisely because ground running hours were not recorded, not sure what the TBO on these engines would be, but I doubt a few hours of ground running, probably at low idle would be that significant in the big picture - the problem here was totally unrelated to engine wear!

[S-Works]

It matters little what you think. The law requires flight time to be logged, therefore the ad is likely to be accurate.

I would be more suspicious about seeing the numbers different is its likely to mean that it's had a problem. A bit like one of our plastics fantastics that's just been nose wheel landed at 128hrs. That's going to have different numbers.....:p

Turbines are done on cycles and on airborne time. Ours tend to run out of cycles before engine life due to the short run duration of our flights. Our gas generators sit at 60% on idle but the real issue on a turbine is the start process is really hard on the engine. I even with the IELUs the starts are a high temp event and this causes more wear on the engine than running at cruise power.