In looking at purchase options, it was suggested to me by a parent they'd really like me to have Auto Pilot.

The plane I looked at this past weekend doesn't have it.

I can buy a used system (pulled from a Maule) for say $3k - since the system available is one on the Maule optional equipment list, is it something that a person would be able to do a 337 for and "install per Maule installation drawings" and negate the need for an STC from STEC?

If its a Century autopilot from a Maule it operates with aileron steering. If Stec on a Maule it is rudder steering.

What is the autopilot going to connect to? If it's a GPS, then compatibility is a factor to consider before buying an autopilot.

Thanks Andy and Jeremy -

The rudder steer for STEC gave me a pause- but I think the Century system requires a yaw damper, or at least the chart I saw showed it as a requirement, so obviously the rudder is a key element to any AP with these airframes.

There is no modern GPS or Nav radio in the plane.

I think the question is more "is a used AP feasible because there are factory drawings and the available POH supplement for the system or is the STC still required for installing any system" ?

So more paperwork and procedure than the coupled signal source or usability later.

I think if it's an option on the Maule equipment list for your airplane, then it's already on Maule's Type Certificate and you don't need a STC. If it's not on the list, then you need a STC. Either way, it's a major airframe modification and needs a 337.

andy wrote: ↑

Thu Jun 03, 2021 7:40 am

I think if it's an option on the Maule equipment list for your airplane, then it's already on Maule's Type Certificate and you don't need a STC. If it's not on the list, then you need a STC. Either way, it's a major airframe modification and needs a 337.

I’m not sure that’s correct. If it’s on the equipment list, and Maule has drawings for it, then it should just be a logbook entry.

Agree with Andy since it is on the AML. S-tec is another story. If it is not an exact autopilot pulled from a Maule, I’m not sure if they will reconfigure it... seems they weren’t very cooperative on adapting used gear. Maybe a call to them would answer that.

Kirk

Kirk wrote: ↑

Thu Jun 03, 2021 8:46 am

Agree with Andy since it is on the AML. S-tec is another story. If it is not an exact autopilot pulled from a Maule, I’m not sure if they will reconfigure it... seems they weren’t very cooperative on adapting used gear. Maybe a call to them would answer that.

Kirk

I had read the same about STEC, and was looking to not deal with them at all if I could help it.

The price of a used system pulled from a Maule is affordable and I think some friends of the family would be willing to help me with a 337, but they wouldn't be able to deal with STEC.

Appreciate everyone lending their thoughts. I know hypotheticals so often have folks scratching their head and wondering what kind of goofball they're dealing with

The reason that I think an autopilot installation would be viewed as a major repair or alteration is due to 14 CFR 1.1's definition of a major repair as:

Major repair means 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

If an autopilot was incorrectly installed, it could definitely have an appreciable affect on flight characteristics since it connects to a flight control surface, whether rudder or ailerons.

You have a reasonable point there, Andy. Your interpretation may well be correct: that it is required in this case. To be honest I would have just done it on a logbook entry, but there is no harm in submitting the 337, and it could possibly keep the FAA off your back at some future moment.

To be clear, we are talking about a 337 for a major repair, NOT a field approval. So the IA fills it out, signs it, and sends it directly to Oklahoma City to be entered into the permanent records for that aircraft. No requirement for a sign-off from the FSDO (or anyone other than the IA).

The main issue of this discussion is a Major Alteration; not a Major Repair. A 337 will be required. The approval for this modification is included in the AML.

riverbuggy wrote: ↑

Sat Jun 05, 2021 6:36 pm

The main issue of this discussion is a Major Alteration; not a Major Repair. A 337 will be required. The approval for this modification is included in the AML.

But in that case, it’s not a major alteration, or an alteration at all, as that refers to alteration from the type certificate. Since they are on the AML, they are de facto included in the type certificate.

This is a useful discussion that made me do more research. I've changed my mind about the 337 as a result. I think Andy Y is correct that a logbook entry is all that is needed. Here's my logic.

The 14 CFR 1.1 definition of "major alteration" is:

Major alteration means 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.

The next question is whether or not inclusion of the autopilot on the optional equipment list means that it IS listed in the aircraft specifications. Note 6 of Type Certificate Data Sheet 3A23 applies to all models and says "Note 6 Equipment approved for all models is listed on the Required and Optional Equipment Lists". I think that is sufficient to conclude that an autopilot on the optional equipment list is approved in the aircraft specifications.

I'm with Andy Young BUT... it's not that easy. If you're thinking S-Tec, Maule's drawing #9212A is not really a drawing. Instead it is a description requiring one have s-tec's Bulletin 973 and their drawings. Try getting that from S-Tec. I did. They sell the bulletin, new harness, and new mounting bracketry as a package. For the model 30 that goes for $8,000. Kind of puts that $2,995 used unit cost within a couple thousand of a whole new kit. Obviously s-tec sells the intellectual property. The hardware is incidental.

gbarrier wrote: ↑

Wed Jun 09, 2021 8:39 pm

I'm with Andy Young BUT... it's not that easy. If you're thinking S-Tec, Maule's drawing #9212A is not really a drawing. Instead it is a description requiring one have s-tec's Bulletin 973 and their drawings. Try getting that from S-Tec. I did. They sell the bulletin, new harness, and new mounting bracketry as a package. For the model 30 that goes for $8,000. Kind of puts that $2,995 used unit cost within a couple thousand of a whole new kit. Obviously s-tec sells the intellectual property. The hardware is incidental.

Thanks for sharing the experience of basically doing what I was looking at.

It's difficult to not wish they'd experience some isgnificant price pressure from TruTrak / BK