Prop Overhaul

[Independence]

Question from a dumb pilot. Does the 10 year overhaul time (constant speed prop) start from when it was overhauled or from when it was first installed on the aircraft?

[SeptRepair]

The ten year overhaul intervals mentioned in (a) and (b), start either from its initial date of installation following manufacture, from its last five year corrosion inspection or its last overhaul, whichever occurred last.
(amended 2000/12/01)

[sportingrifle]

Sadly I don't think that this was the intention when it was written, but this is the result. Buy a brand new Hartzell CS prop in a crate, leave it in your heated basement for 11 years, and you are good to go. Buy a new overhauled one with the same grease and seals in it, leave it for 11 years in the same box, in the same heated basement, and it is toast.

This whole 10 year thing was dreamed up by the prop shops a number of years ago. (I know exactly how this went down because my AME was on the CARAC committee at the time) It is interesting to note that in the US they don't have this requirement and C/S props are not parting company with airplanes at any significantly higher rate. (They are however, anecdotally according to my US prop shop, not making overhaul at a higher rate.) At the end of the day, calendar time is a broad brushstroke. An airplane that lives in a hanger in Arizona and is flown every month can probably go 30 years between overhauls. A floatplane that lives outside in Vancouver and doesn't turn a prop for six months every year is probably pushing its luck for 5 years.

Cheers sportingrifle

[Heliian]

^ it's not the same. A brand new assembly would have been properly preserved and most likely sealed with desiccant. The calendar inspections are to prevent people from putting rotted out parts on their aircraft. It's not a conspiracy, there are many documented cases of corrosion induced failures.

[sportingrifle]

Helian....

I can only speak of my personal experiences, sample size of 1.

My factory new Hartzell CS prop came packed in factory cardboard box, no dessicant, and just Aeroshell 6 grease in the hub. Just like my many overhauled Hamlton Standards, except my shop sends them out in plywood crates.
My comments about different climates and failure rates came more or less verbatim from the manager of my US based prop shop that has been in business for over 30 years and does a lot of work for Canadian customers. The NTSB/FAA/TSB/TC data bases are incomplete and difficult to get data from, but apparently there are no significantly greater rates of corrosion induced failures in the US fleet. As I did mention however, (sample size 1 again) my shop says that they reject many more parts at overhaul from US props due to corrosion. YMMV. sportingrifle

Cheers sportingrifle

[anofly]

I have also heard from a Canadian prop shop that american props with lots of time on them, need more parts and money to get back to airworthy standards. Lots of "forum" traffic in USA about "reseal" inspections . They take em apart, look for obvious corrosion, measure nothing, clean them up , new grease and seals and put em back together with a bit of paint of course. For private flying it is ok to do this, but when they eventually get overhauled there is a lot more buying of parts and new props happening down there. I know of one prop type that ended with an expensive AD due mostly to "lack of maintenance" south of the border (on an admittedly old design) and of course a few poorly maintained examples eventually threw a blade.. then the fun started.... In Canada we all paid for that AD, and probably due to our overhaul requirements, there never would have been a similar failure in Canada.

[Therewewere]

Perhaps someone could explain to me why a Constant Speed prop has been mandated by TC for a 10 year overhaul, however Fixed Pitch aluminum props (McCauley) have to be overhauled every 6 years. There is a provision for a 5 year dimension and corrosion check, which suddenly our AMO can no longer do and we have to send them to the prop shop where the cost is only about $300 less then an overhaul. This just seems incredibly stupid. Its just a hunk of aluminum with no moving parts!!