TBO of R-985

[Widow]

This Service Difficulty Advisory says

The basic TBO of the R-985 is 1200 hours with a possible approved extension to a maximum of 1600 hours.

Does anyone know on what criteria this extension would be based?

[fgrimes]

I'd say based on operator experience. Contact your PMI at Transport. He is there to help you

[small penguin]

I would have thought send the engine manufacturer an email. Either that or Google, though Im not sure Google would turn much up.

[Strega]

I would have thought send the engine manufacturer an email. Either that or Google, though Im not sure Google would turn much up.

Thats a good one!

[twotter]

It is mostly based on satisfactory tear down reports from your engine overhaul facility. If you start at 1200 and send an engine in for overhaul and the teardown report shows that it could have gone longer you "may" get and extension to 1300 or 1400 depending on TC's mood that day.. If your engines only go to 1000 before you send it in for overhaul, you may have an issue with getting the extension.. It will also depend on what you are doing with that engine but for most Beaver operators this will be the most important..

[Bulawrench]

R985 overhaul period for commercial operators varies throughout the planet. Yes, there is local authority approval but no more than 1600 hours. The sliding counterweight on the crankshaft has an airworthiness directive. Depending on the maintenance they will start to blow up anywhere from 1200 hours and on.
There originally were 800 hours TBO

[Cat Driver]

The bottom line is the engine time is in direct relation to how the engine is operated...it only takes one throttle monkey to drastically reduce the life time of a radial engine.

[Spinner]

If I remember right (it has been 18 years) the TBO on the 985's were extended to 1400 from a starting point of 800 or 1000 hrs. As said prior if the teardowns were decent TC would allow a time trial of one or two engines to another 500 hours over the current TBO of the company.

The 1340's only had a 1200 TBO and never seemed to get real close to that number. As cat says the person operating the aircraft can have a lot to do with how close you get to published TBO

[Bulawrench]

Yes, throttle monkey. Also what quality is the overhaul. I have been struggling with a couple of poor overhauls. High oil consumption,leaks and broken cylinders. You get what you pay for.

[ruddersup?]

Yes Spinner, I had 1400 as standard TBO back almost 30 yrs ago plus extension earned. I found them able to go much higher but its all up to the pilot. Of course this is on all engines, huh?

[Widow]

So, would it be an acceptable practice for a single pilot privately operated aircraft with a TBO of 1200 to go commercial, add aircraft and pilot(s) and immediately get a TBO extension to 1600?

[PITA]

When changing from one maintenance schedule to another there is a foumula used to determine the time remaining until overhaul CAR's 625 appx F I believe.
X = Y x A/B x = time remaining on new program
y = time remaining of previous program
a = interval on new program
b = interval on previous program.

So a previous program of 1200hrs overhaul limit with 800hrs on the engine.

x = 400 x 1600/1200 = 400 x 1.3 = 533hrs remaining on the engine with the new mtce schedule.

PITA

[Bulawrench]

That is very good info. The other item that i see is the way time is logged. Flight time instead of hobbs time is approx 21% lower. This means that 1600 is actually 1800 hours. It is an operator's way of squeezing more time.
The longer the engine is worked the more worn out it gets. For the R985 when the crankshaft end play gets to be too much the crankshaft can be damaged and unusable for the overhaul. Really false economy.