strut replacement documentation

[Nefj40]

Re: strut replacement documentation

AA struts are STC'd. The front struts are 4 inches across where the Tcraft struts are 3 inches. The rears are the same as the originals. Weight wise the AA fronts are lighter but the rears are heavier so it come out awash. Weights where done on a certified UPS scale.

[Garry Crookham]

Re: strut replacement documentation

There really is no end to the ambiguity and recursion is there?

Dave R

I agree. That makes it hard for an airplane owner to figure all of this out. And yes, 14CFR Part 1 does define "minor repairs and alterations."

Re: strut replacement documentation

I have to disagree. If the strut has a PMA and is listed in the PMA holders eligibility list then it can be installed as a minor alteration. I believe the Airframes struts require an STC because they are considerably larger than original.

Hi Garry,

I would not have called it an alteration but rather just a repair/replacement.

However regardless of what it is called I agree that it is not major but a minor and is a "logbook" entry.

Dave R.

[Garry Crookham]

Re: strut replacement documentation

The PMA alone is not enough.

I have to disagree. If the strut has a PMA and is listed in the PMA holders eligibility list then it can be installed as a minor alteration. I believe the Airframes struts require an STC because they are considerably larger than original.

[astjp2]

Re: strut replacement documentation

Dave, if you were building the 1.5" axle gear I would be interested....but I want good brakes.

[PA1195]

Re: strut replacement documentation

The other possible anomaly with Airframes' struts is their chord is slightly offset relative to the aircraft's fuselage level or thrust line. Their chord visibly follows/is parallel to the lower fitting and adjacent longeron to which they're attached. Maybe they all do that regardless of manufacture?

Picture: http://www.airframesalaska.com/Taylo...-tcraftset.htm

Gary

Re: strut replacement documentation

My take on Airframe's struts is that they're FAA/PMA and STC'd because they may be made from strut material used for other aircraft like Pipers...wider chord or some other spec like material. They resemble Piper Cub struts. I was told they were 2# lighter the set than the OEM struts. Didn't confirm that however.

Gary

Hi Gary,

There were Taylorcrafts made with the wide cord material like the Pipers.

Not a lot but there were some.

I am working on a PMA for the taper axle and the ACO seems willing to do it by STC (and associated PMA for STC parts) or by PMA only for a direct replacement part (no STC).

The difference in the two from the perspective of the applicant is ease of processing the paperwork.

Dave R

[PA1195]

Re: strut replacement documentation

My take on Airframe's struts is that they're FAA/PMA and STC'd because they may be made from strut material used for other aircraft like Pipers...wider chord or some other spec like material. They resemble Piper Cub struts. I was told they were 2# lighter the set than the OEM struts. Didn't confirm that however.

Gary

Re: strut replacement documentation

All parts are required to be PMA'd or other spec like a TSO, etc. unless there is a drawing to build an owner produced part. It still may require an STC...its like saying that your airplane has a Lycoming O-320 and you replace it with an O-360, both are PMA, but there still needs to be approval to install it. The PMA alone is not enough. The airframes struts have a PMA, that is the approval to build them, they also have an STC because they are not the OEM.

Yes STC's require PMA for their parts too.

There really is no end to the ambiguity and recursion is there?

I suspect that when many of us say "PMA parts" that we also mean "no STC" even though it is unspoken.

Dave R

[astjp2]

Re: strut replacement documentation

All parts are required to be PMA'd or other spec like a TSO, etc. unless there is a drawing to build an owner produced part. It still may require an STC...its like saying that your airplane has a Lycoming O-320 and you replace it with an O-360, both are PMA, but there still needs to be approval to install it. The PMA alone is not enough. The airframes struts have a PMA, that is the approval to build them, they also have an STC because they are not the OEM.

[Garry Crookham]

Re: strut replacement documentation

This discussion is probably a bit confusing to most aircraft owners without a maintenance background. PMA stands for Parts manufacturing Approval. A company that wants to produce parts to be installed on a type certificated aircraft is required to get a PMA on the parts to be produced and cannot legally produce the parts for sale without a PMA. The PMA part is usually an identical replacement for the subject part, or could have minor modifications that the PMA holder has cleared with the FAA. If a major change has been made to the part then an STC is usually required for installation. A part with a PMA is considered an approved replacement part if it is listed on the PMA holders eligibility list ( a list detailing what aircraft the part can be installed on). Parts produced by the aircraft manufacturer don’t need a PMA since they hold the type certificate for the airplane.

Per the strut discussion: If you purchase PMA struts (make sure your aircraft type is on the eligibility list) a logbook entry is all that is required. If the struts are an STC item then a Form 337 is required since it is considered a major alteration. And if you purchase the struts from the aircraft manufacturer a logbook entry is all that is required.

Re: strut replacement documentation

It all depends on if the WAG strut was built under an STC, if so, just do a 337 for installation compliance.."installed wag aero strust part #---- IAS stc ---, this is terminates repetitive inspection IAW AD---Para.--- section---. Weight and balance updated as required. END" and then just mail to OK city. Then a corresponding log book entry, "installed wag aero struts per stc---and AD--- see faa form 337 dated ---. signature, date cert. number. no fsdo involvement because the data is already approved by the STC and AD, the installation is approved by the IA's signature for return to service.

Good point about if they are STC'ed maybe some are but WagAero's and Univair's are PMA parts.

[astjp2]

Re: strut replacement documentation

It all depends on if the WAG strut was built under an STC, if so, just do a 337 for installation compliance.."installed wag aero strust part #---- IAS stc ---, this is terminates repetitive inspection IAW AD---Para.--- section---. Weight and balance updated as required. END" and then just mail to OK city. Then a corresponding log book entry, "installed wag aero struts per stc---and AD--- see faa form 337 dated ---. signature, date cert. number. no fsdo involvement because the data is already approved by the STC and AD, the installation is approved by the IA's signature for return to service.

Re: strut replacement documentation

Hi,

I see.

From part 43 appendix A there is this summary heading defining major repairs;

(b) Major repairs—(1) Airframe major repairs. Repairs to the following parts of an airframe and repairs of the following types, involving the strengthening, reinforcing, splicing, and manufacturing of primary structural members or their replacement, when replacement is by fabrication such as riveting or welding, are airframe major repairs.

Replacing struts with PMA struts does not qualify as a major so it is merely a logbook entry.

The AD has re inspection requirements for the fitting but that may actually be a separate AD I don't recall but he should read that and comply when he does the strut installation.

As the owner you are required to keep the AD status not the A&P (see part 91) so make sure you keep a nice set of records.

Dave R

[hangarb7]

Re: strut replacement documentation

Sorry Dave, I guess I wasn't clear.

I just contacted him yesterday and he hasn't even met me or seen the airplane. He just asked that on the telephone call.

Jack