20+ year old aircraft - But Low TTIS.
 

Talking to a chap the other day who was considering purchasing a cabin class twin, Chieftain, Aerocomander, Cessna etc.

There are some interesting aircraft up for sale around the world. An interesting site is Mike jones aircraft sales who do their Lock and Key Chieftains and Navajos. One aircraft is listed as only 1600 hrs TT for a 1981 airframe. They want nearly 1 million USD for it. These aircraft are probably refurbed to a better state than when leaving the factory. Nonetheless the load bearing bit, spars, ribs etc. are still approaching 30 years old.

How can one tell if all the corrosion has been found and eliminated. Would it be more sensible to replace the spar in its entirety.

You might want to talk to a few LAMEs about this.. old airframes with very low hours usually means they've sat around doing nothing for extended periods of time. This is bad news for engines (the moisture does damage), and not really good for airframe or systems.

Unless you're talking very high time (ie getting into component restriction territory), it's probably better to get a higher time, slightly younger model which was continually utilised and maintained.

A long time for engines sitting around is not necessarily a problem due to the life limit of 10 years anyway, so if it was just over 20 years old, it might have Zero time engines as they would have been replaced or rebuilt anyway!

Correct me if I'm wrong on that one...

I'd go an unflown hangared aircraft of 20 years over a thrashed machine that's been kept outside for 5 years - common sense prevails there my friend! Do you think a car would be in worse condition after being garaged for 10 years than one used every day for 5 ?

The 10 year life for aircraft engines only applies if the aircraft is operating in charter or Class A catagory. If the aircraft is in private or airwork catagory then the engine can run "on condition". Although i admit that most cabin class twins around would be operated in charter catagory.

As for old, low time airframes it all depends on circumstance. If said plane was hangered in a dry environment, corrosion inhibited, all bearings regulary worked and lubricated, engine regulary ground run, etc then it could be ok. Remembering that all the radios, gyro's, instruments and possibly wiring will cause many headaches when they are returned to service after years of "static display".
Unfortunately this is rarely the case. Useally aeroplanes arn't flown because the owners either can't afford them or don't care about them so are unlikey to spend the extra coin on a nice hangar and regular preventitive maintenance.
Give me a 5000hr C172R ex flying school plane over a low time, corroded out, H2AD engined N model anyday!!!!

JS:ok:

XXX the problem is not the legal limit but the maintenance bills you're likely to incur on an old, moisture-infested, underused engine.

Experienced engine overhaulers suggest that an aircraft engine should be run at least an hour every week on normal cruise power.

Our company bought an Islander (300Hp model) from the Portugese AirForce that had been sold to them as a VIP transport for their Air Marshal (I would have loved to meet the salesman who sold it to them for that:ooh:).
It was in great condition though it had only flown 400hrs in 10 years (I wonder why ?).
Out came the toilet and all of the double glazing on the windows and it went on to start earning a living as a hard working geosurvey platform.
Within two hundred hours, we had to replace BOTH engines as there was major spalling on the lifters and camshafts along with glazed bores and frequent cracked cylinder rings.
The bigend bearings all had corrosion/spalling issues that ultimately kept clogging up the oil pressure bypass valves, hence the decision to rip 'em out and get on with our lives.

Once the control rod bearings had all been replaced, the aircraft went on to be as reliable as any Islander can be and ultimately ended up being a great machine.
So, the moral is...be prepared to spend money initially, but a low time old aircraft CAN be a good buy if you get it for the right price.

It could have sit in the desert for a while which would have brought its hours down, and for an aircraft like that get a lame to scope it out, not saying they are the end all and be all, but they know where to look

On that point, maybe redd this

cpaahomepage06

Terrific article Cleared, and timely too.

This is becoming a real problem with aircraft all over the countryside with Avgas going through the roof, many owners keep putting off flying until they realise that six months has gone by since their pride and joy made a noise.

The corrosion described in the article is almost guaranteed unless steps are taken and the cam lobes/lifters get it first.