PA39 purchase - help please

[BusDriver]

Hi All,

I'm in the process of negotiating the purchase of a PA39.
The aircraft is due a couple of recurrent inspections, and i'd appreciate members guidance on estimating the worst case labour time and parts cost associated with the 1000 gear inspection and the Stab horn inspection.

Thanks in advance.

[N3322G]

Marcus,

Welcome to almost Comanche ownership. I have a 39 and the stab horn inspection is not required for Twins thanks to a lot of work by ICS and Hans Neubert.

On the gear AD, mine has always been done as a part of an annual so I can't break it out cost-wise. If I had it to do again, rather than inspect and use go/no-go gauge, I'd simply replace all the inspected bolts and bearings. Others on this forum have done that and may be able to share their experience.

Who did the pre-buy? They may be able to ballpark a cost for you.

[MULEFLY]

Bus.... call Cliff Wilewski, Heritage Aero, Rockford, IL... 815-395-0500. He is one of the technical staff of ICS and he and his guys probably service 2 to 3 dozen Comanches annually. I'd post guesses, but Cliff is doing these all the time. If you do as Pat suggests on the 1,000 hour... the parts alone will be north of $2K. If you go/no go... obviously, if they pass, quite a bit less.

Jim

[BusDriver]

Thanks, it all hinges on the current owner changing his price aspirations!

N3322G - thank you.
I had no idea that the Stab horn SB was no longer required - could I trouble you for a reference for this?

Mulefly - thank you.
I'll definitely give Cliff a call tomorrow.

The very reputable maintenance organisation that currently looks after the aircraft are quoting £200 ($300) and describe it as a "clean and inspection only" which doesn't sound right to me.

Regards,

Marcus

[MULEFLY]

Marcus... 1000 hour inspect only no replacement of parts -- probably a minimum of 8 hours ... bushings have to be heated and hand reamed if replaced ... so if you replace parts then significantly more... for only $300 -- you get what you pay for.

Jim

[Kristin Winter]

Marcus,

The service bulletin is still in effect. It is not mandatory in the U.S. as the AD did not include the twins. Are you planning on putting this on overseas registration? There are two SB's -- SB 1160 and SB 1189. SB 1160 calls for inspection of the torque tube for corrosion and replacement if it does not meet specifications. It is recurring every 10 years. SB 1189 requires disassembly of the tail and a dye penetrant inspection of the torque tube/balance arm horn every 100 hours or 1000 hours if a new horn is installed. This is an SB that is founded on bad engineering assumptions as it assumes that the cracking is fatique related and it is not. The cost of disassembly of the tail and replacement of the torque tube and horn is about $1,100 for parts and eight or so hours of labor. $2,000 is a good ball park.

The 1000 hour inspection is likely to run at least 20 hours of labor for the bare bones inspection and parts can be north of $2,000. Without parts, $2,000 is a reasonable estimate. If you need welding repairs, the price goes up. I can better tell after inspecting the condition for the landing gear.

Often the landing gear wiring is in poor condition. That airplane has the newer microswitches so it is not terribly cheap to redo those. A complete replacement of the wiring harness on a PA-39 will run close to $2,000.

Do you have someone lined up to do a pre-purchase inspection? You need someone who knows the Comanches, especially the twins, very well. There are a number of other things to look for. If you want more information, email me at kristin_winter at comcast dot net.

[N3322G]

Marcus,

As others have stated Twins are not on the stab AD. The SB is still in effect. If you have this done, be sure the mechanic uses the proper techniques.

[BusDriver]

Thank you everyone for your great advice.

It is nice to know that there is such a wealth of knowledge available and only a few keyboard clicks away.

The aircraft is on the 'N' register and is based in Europe. Although SB adherence is not mandatory I personally feel that it is sensible to treat them like AD's. Especially when dealing with the landing gear and the only means of pitch control.

Thanks again,

Marcus

[Kristin Winter]

Careful maintenance that goes above and beyond the minimum is almost always a good thing. However, in this case, SB 1189 should only be done once. The 100 hour repetitive requirement, even for the singles, is wrong-headed and compliance every 100 hours will do more damage to the aircraft than will ever be prevented. Removing the stabilators that often will eventually wear out the tight fit between the fittings in the stabilator and the torque tube. Once you have ruined those, you will be left needing to scavenge for used serviceable parts.

I think everyone should take about their 40-50 year old tails once to clean everything up, check the bearings, etc. Then if you are not affected by the AD, leave it alone for a dozen years or more.

[N3322G]

Ditto Kristin's approach.

When the stab issue was first raised, I had mine checked and it helped support the lack of AD on the Twin's as no trouble was found.

When the SB came out, the shop I use today was trained on it and I declined their offer to comply with the SB as the inspection was already done so just to comply with the SB didn't make sense to me.