Cessna 120-140 Association

Im wanting to replace the Remy-Delco generator in my '47 140 with an alternator (as I assume many have done). In my research I have found that Plane Power Inc. Makes a direct-drive alternator for our aircraft. It is the JASCO unit, and runs in the neighborhood of $3700 (gulp). Hartzell hold an STC for the ER14-50 Hartzell Plane Power Alternator (sold by Spruce for $2400) Apparently that STC (SA10921SC) covers the 120/140. Has anybody here made that conversion, and do you have any advice or comments as to the conversion, STC, or installation? Those who have made the conversion, ANy hassles with the STC?

Thank ya.

Marc,

Take a look at this video which shows installation of the Plane Power 50 Amp Alternator installation on a Cessna 120 with an 0-200.

https://youtu.be/ur2WnJdU6vo?si=EWaG3Vf2J8ZciY3v

Installation is pretty straightforward, but there are a few items that will be required to accomplish the installation such as the usage of heavier gauge wire, and an alternator circuit breaker (available from Stein Air or Spruce). Additionally take a look at the Plane Power web site in order to see the drawing and instructions for the installation. I would highly recommend that if you elect to install the alternator also replace the drive coupling (Part# 07-01348 MFR Model# G-PACK) again available from Aircraft Spruce. One last item, don't forget repeat don't forget to remove the drive gear off your existing generator before you turn it in to Spruce as a core. You'll need that gear to install it on the alternator shaft.

https://planepower.aero/aircraft-altern ... tructions/

This is excellent. Thank you!

Marc:
Considering the high cost items, you may want to look in to just duplicating the Cesna 150 O-200 charging system installation on yours - using all Cessna parts, alternator and controller (regulator).

Suggest you read FAA Part 43, Appendix A (not AC43) which clarifies what are "major alterations" and thus, anything not major is minor (log book entry). Specific to you, Part 43 Appendix A (a)(xii) "Changes to the basic design of .....electrical...". Just upgrading to an alternator can be construed to mean no change to the "basic design". Yeah, I know this is "out-of-the-box" thinking, but it has been mentioned on this page some years ago by one who knows the finer points of the regs.

IIRC, many years ago, there was a guy selling only the paper STC to accomplish the chamge, with the owner providing his own parts, but he did have some alternators. I think he went "west" and his son took over. One of the moderators may be able to check archive pages for a contact, to see if still available

Also, a field approval may not be too difficult to obtain - depending on your area FSDO. May ask here, if anyone has a copy of one to support. FWIW

Put the Plane Power conversion kit on my 120 about 3 years ago. Works great, no regrets. Easily powers a fairly full panel and lights.

I have the Ford alternator installed with a field approval. I referenced the Cessna 150 wiring diagram and parts list and AC43.13-1B chapter 11. My PMI signed it off and Bob's my uncle.

have the Ford alternator installed with a field approval.

Same here on my 0-200 previous owner did. $675-ish, a new amp meter and some wiring changes, and now have the Zeftronics voltage regulator to replace the old points contact unit.

Only downside I see is it's not light weight but it's bulletproof.

IMHO opinion anything that takes weight away from ahead of the cg in a 120/140 is a good thing. Granted I have a 1946 model without extenders, but would still go for the Plane Power just for its weight savings. And functionality.