Part# 07-03565
MFR Model# STS-M24


FAA-PMA APPROVED for Certified Aircraft

Continuous Duty (Battery/Master Solenoid). Available in 12V and 24V. Activation: -(Ground) to S-Terminal. (Floating ground frame).

All stock meets Service Bulletin 72.


  • Silver Contacts provide 300A in-rush & 150A continuous-duty capability Much higher than OE units
  • Light spring and low-current coil for excellent engagement and holding capability
  • Single coil terminal (other end of coil connected to Battery terminal)


  • FAA-PMA Certified - stop using automotive parts and operating in the 'gray area' (aka. non-conformance) of the FAR's!
  • Lamar has retooled & upgraded the GOOD, "old-school" aircraft solenoids!
  • High Quality Manufacturing designed to take the beating our piston aircraft dish out
  • Upgraded to perform best with today's lightweight, high torque starters
  • Not automotive store parts with extra mystery terminals
  • Same OE terminal layout used for decades on our aircraft - simple to install
  • Silver contacts (vs. copper) for high-current capability and long-life
  • All-metal case construction
  • Frequently Purchased With
  • Customers Also Viewed


Worked great. Replaced 3 pole legacy unit per drawings.

Stephen C Verified Purchase


July 26, 2022

Silver contacts should give good service

James C
March 15, 2021

Performed exactly as advertised. Quality product. Outstanding service.

Dennis E
December 22, 2020

Fits & functions fine.

Ken S
October 23, 2020

A perfect replacement for the 3 post contactor on my Cessna 150.

Serloyd L
October 2, 2020

Exact fit and replacement for my old one. Works perfectly so far.

Richard C
August 17, 2020

Product came as Advertised. As always I never had any problems with the great service Aircraft Spruce provides. Thanks

Peter S
June 8, 2020

so far so good

Richard J
March 15, 2020

Good fit. Solid construction. No more jiggling battery leads to get relay to engage.

Steven A
February 19, 2020

to replace an original equipment solenoid in my OLD Mooney, this is the only game in town (and at a reasonable price too). it fit just fine and operates exactly as expected. as usual, no complaints with anything from Aircraft Spruce.

T. D
March 7, 2019


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: What is the total current draw of the solenoid when actuated?

The total current draw is 0.8 amps.

Q: What is the difference between STec-A12 and STec-M12 relays?

The STS-M12 is for the battery master. The STS-a12 is for Auxiliary master, like a GPU.

Q: What size are the power and coil terminals? Also what is the recommended mounting orientation? I note that the 11-03161 (White-Rogers) unit recommends Cap Down orientation.

The coil terminals are #10's and the power terminals are 5/16ths. It is recommended to mount per the airframe specifications. If none, it is recommended to mount with the cap up.

Q: Does this Lamar solenoid include the diode? If not do I need it and what part number would it be?

Per Vendor: This product does not include the diode. You do not need the diode for the part to work correctly, it is simply a safety precaution some like to take. The airframe manufacturer might have a diode they recommend.

Q: What is the warranty for this unit?

12 mo from date of installation of product or 500 hrs - whichever comes first. Log books are required for warranty

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