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Part# 11-04227
MFR Model# MS25041-10


Miniature press-to-test indicator with built-in bulb testing device. Adjustable dimmer. Uses #330 (12V) or #327 (24V) bulb. Bulbs NOT included, order separately.

Part numbers for replacement bulbs are 11-04016 (GE-330) and 11-04015 (GE-327). See "Accessories" tab to purchase.

Reference Chart

Part No.
Press-To-Test MS25041-1 Clear
Press-To-Test MS25041-3 Green
Press-To-Test MS25041-10 Blue
Press-To-Test MS25041-2 Red
Press-To-Test MS25041-4 Amber


  • Accessories
  • Frequently Purchased With
  • Customers Also Viewed


Unchanged in 50 years. Did the job for the Navy then, works good in the Bo now.

Thomas W
February 22, 2021


John E
August 24, 2020

They are very well done and They work.

Mauricio F
June 13, 2020

Used this as my ads-b ‘fail’ light. Worked out great

April 30, 2020

April 18, 2019

Fast shipping, easy order placement, thanks!

March 23, 2017

The press to test light came without a bulb in it’ How disappointing!

Dan E
November 25, 2019

I was surprised to find that the dimming of the bulb is accomplished by a shutter, similar to what controls the amount of light coming through a camera lens and not electrically controlled. Not bad just different. Not installed yet. Just bench tested.

April 12, 2018

As expected... would have been nice if they would include wiring diagram..

April 25, 2019

Good quality, a bit over priced. Do not forget to order the bulb sold seperatly!

Mike K
March 8, 2018


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: It says miniature but does not mention a size. What is mounting hole size and diameter of light?

The mounting hole should be approx 15/32", and the lens is .650".

Q: What are the part numbers for the bulbs?

Part numbers for replacement bulbs are 11-04016 (GE-330) and 11-04015 (GE-327). See "Accessories" tab to purchase.

Q: There are 3 prongs on the back of Press to test indicator. Which tab is used for which?

There are three prongs labeled labled 1, 2 and 3. When hooked up, 1 is ground, 1 & 3 is on and 1 & 2 is off.

Q: Which 2 prongs on the MS25041 indicators are used for push to test function? 1&2 or 1&3?

We have added a drawing to the 'Documents' tab of this web page. Please review the details by downloading the PDF.

Q: Can the MS25041 press-to-test indicator lights be used in certified aircraft?

Yes, these are MIL spec units and can be used in certified aircraft per the manufacturer.

Q: What is the electrical consumption MS25041-10?

If the aircraft is 14v you would use the ge-330(14V .08A) or if 28v (28V .04A.) It would depend on your voltage.

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