Yoke upgrade?

[NateZ]

Aircraft in question is a '65 M20C that im looking at. The airplane has the new style mooney yokes in it. I asked the owner if a 337/field approval was done for the yoke swap and his reply was "Mooney said a 337 was not needed to install the yokes."

 

Is this true? What is the usual procedure for upgrading the yokes on Mooneys? I swapped out yokes on my twin commanche, and needed a field approval, however in that instance I was using Piper Navajo yokes....

 

Nate

[KSMooniac]

Well, it should be logged in the books somewhere, so check for at least a log entry.  All of the Mooney M20 series are on the same type certificate, and that does make it easier to install later model parts on earlier airframes.  However, I believe the yoke tubes are a smaller diameter on the earlier planes relative to the later ones, so the tubes should have been swapped as well.  I would verify the log entries and make sure the tubes were changed...and hopefully not mickey-moused together.

[Cruiser]

This is always a sticky subject. The 337 is required for MAJOR modifications to the aircraft and must be signed off by the appropriate FAA personnel. Normally these include some description of the effects on the aircraft and its ability to maintain its airworthiness certificate with the modifications.

Your A&P/IA is authorized to make MINOR alterations to the aircraft with only a logbook entry for return to service. No 337 is required.

So, in answer, it all depends..........

depends on the A&P's determination of MAJOR/MINOR and his willingness to signoff

depends on the FAA's interpretation of MAJOR vs. MINOR modification.

It never hurts to have a 337, it could be costly and the aircraft could be considered unairworthy without one.

[N601RX]

Mooney did sell an upgrade kit 940021-501 that contained the new yokes and heavier control shafts, but I think most people just got them from salvage yards.  The FAA list some criteria for determining major vs minor in part 43 and appendix A.  Most mechanics would say minor or let it slide by, but some would not.

I ran into this with the 1 pc rear window upgrade.  After much reading and finding that some mechanics said minor and others said major, We talked talked to Mooney.  They said it was minor and I kept a copy of the letter for my records so if any questions ever came up.

[NateZ]

Thanks guys. Getting closer...

 

Nate

[jetdriven]

Major repairs or alterations are listed as:

(http://www.faa-aircraft-certification.com/faa-definitions.html#M.)

Major alteration. An alteration not listed in the aircraft, aircraft engine, or propeller specifications—

(1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations.

Major repair. A repair:

(1) That, if improperly done, might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations.

 

 

Minor Alteration. An alteration other than a major alteration.

Minor Repair. A repair other than a major repair. 

 

Is replacing a Mooney yoke with a later model Mooney yoke a major alteration?

[OR75]

I installed a 406 ELT a couple of years ago to replace and ELT 200.

The OEM (Artex) told they considered that i was minor and did not require a 337. The IA said it needed a form 337.

 

[jetdriven]

Was he operating in CYA mode or FYA mode?   We swapped out a VFR Northstar GPS for a VFR KLN-89B.  NO 337. 

[fantom]

Quote: jetdriven

Was he operating in CYA mode or FYA mode?   We swapped out a VFR Northstar GPS for a VFR KLN-89B.  NO 337. 

[danb35]

There's a Mooney drawing that authorizes replacing the yokes with the J style on older Mooneys (no doubt it came with the kit, but I imagine it was available separately also).  It was done on mine with only a logbook entry; there shouldn't be a need for a 337, and definitely doesn't need a field approval (it's already approved via the Mooney drawing, as long as the work conforms to that drawing).

[jwilkins]

I would an AP to evaluate this way:

If the change is done in accordance with an existing Mooney Factory drawing, AD 77-17-04 or Mooney SB 205B it is logical to take the approach that the logbook entry stating compliance with the drawing, AD and SB is sufficient. You shouldn't need a 337 when following a factory drawing, complying with an AD, or SB.

The AP does not have to sign off something he / she doesn't like, but you can always discuss it. If you don't like the decision you can ask another mechanic's opinion. These things are frequently judgement calls and vary between mechanics, different shops, and even different FSDOs.

Some of these 'conversions' have been done by cross drilling the original thin wall control shafts for the newer control wheel. I would not accept this even if a mechanic did sign off on it. The original thin wall shafts had the AD for a reason. Field drilling original shafts bothers me. Post 1968 the shafts can be spliced per the SB. If the shafts were spliced in accordance with the SB and cross drilled for the new control wheels and signed off by the mechanic I would not be concerned (although it is not strictly following the SB as I understand it).

Jim

 

Jim