PA 38 spar life and engine

[mad_jock]

Trying to find out a few things about tommy's

There is a spar life on them but I can't remember exactly how long it is. 8k hours seems to ring a bell.

Also the last time I was involved buying an engine it was through CSE in Oxford.

How much are LYCOMING O-235-L2C these days and where would you get one.

[IO540]

Here (http://www.factoryengines.com/) is a good source for engines.

Spar life? I didn't think a PA38 had a spar ;) I did my first 20hrs in them - the whole thing seems to flex like a toy plane :)

[Squawk7143]

MJ,

Lots of references to spar life for PA38 in Google, many references to the FAA type certificate stating 11,000 hours TIS(Time in Service). However I seem to remember my instructor telling me that there was a Spar modification which extended that life considerably.

Squawk

As a footnote, at HFS I was taught to land with stage one flap only ( never stage 2) specifically to go easy on the wingspars on bumpy days in particular!)

[mad_jock]

I tried Yahoo and all it came up with was bloody pprune threads.

will try google

There was a mod but you had to get it done before 2/3rds of the life or something like that.

O aye bog off IO there a cracking wee plane :p

That was a Pete theory which is no way backed up by any engineering fact. The wing loading is the same what ever flap setting you had it at all you do by using flap is alter the speed which said load is at and your attitude. The things were design to be landed at full flap and the fatigue life limits are set for that design load including gust factor. Any benefit to the structure will have been negated by the students day in day out planting them on the runway and trying to rip the wings off recovering from spiral dives and doing steep turn lesson 5-6 times a week.

It is more of the case though that if you don't have full flap on and the student pulls the power on you early the instructor has more time to sort the problem/ its easier to sort out before the impact with runway he probably started doing it after the nose gear collapsed accident. But it doesn't teach you how to fly and land the aircraft properly and fills your head with pseudo technical bollox

['India-Mike]

The airframe is indeed lifed at 11,000 hours. I think it isn't a spar problem as such but a spar attachment issue. I believe that there is an STC that will extend the life, I think to 18,000 hours. A CAA DLS acquaintance of mine was working on getting the STC approved on behalf of a UK applicant (can't remember who that was) in the UK but that was 3 years ago. Either it'll be approved by now, or that applicant will have become pi$$ed off and withdrawn! My further recollection was that the mod would cost £5.5k+VAT. At today's airframe values I'd throw the bloody thing away and buy something else!

[smarthawke]

The wording re life limits on the PA38 is in the Maintenance Manual and in the Type Certificate Data Sheet:

'PA-38-112 - all S/N:
(a.) The service life of the wing and associated structure has been established as 11,000 hours time-in-service.'

'Associated structure' - is normally taken to be the carry through spar/frames in the centre fuselage.

There is a mod out to re-life the spars but it isn't cheap, not sure if it is EASA approved.

If you want a factory engine, go through Piper & CSP Parts at Shoreham, if you want an engine overhauled, try Nicholson-McLaren Aviation in Wokingham.

[Lima Foxtrot]

Spar Mod - enjoy! (http://www.sterlingaviationtech.com/store/shop.mvc?Screen=PROD&Product_Code=SA500&Category_Code=001)

[mad_jock]

Cheers for the links much appreciated.

[Brooklands]

The service life of the wing and associated structure has been established as 11,000 hours time-in-service.'

Intersting as there seem to be a few Tomahawks on G-INFO with totals hours in excess of that*, unless of course, the total hours on G-INfo are measused differently from time-in-service hours.

Brooklands

*No, they've not been deregistered, at least not when I checked just now

[astir 8]

Is there really a big and abrupt section change in the normal spar as shown on that spar mod link? My old engineering teachers wouldn't have given me many marks for a design with such a stress concentrating step in it!

[mad_jock]

Its fairly typical of American engineering of that day. And tapered sections of composite beams weren't as easy to manufacture as they are today. But then again I was a common FEA stress engineer there could be a heap of factors that I haven't a clue about with aero design.

All that mod does is put a fillet in the stress concentration and put the bulk of the load onto some fresh metal.