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Aero Safety Systems AH501 Master Caution / Master Warning Switch

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The AH501 is combined Master Warning and Master Caution annunciator and combined with a high quality snap action alert acknowledgement switch. The AH501 allows the pilot to quickly recognize, acknowledge and mute new alerts and is ideally positioned directly in front of the pilot, just below the coaming for bringing alerts to your attention while keeping your head up.

The unit can be wired as a remote Master Caution and Master Warning Annunciator for common EFIS systems such as the Garmin G3X and Dynon. When combined with the Aero Safety Systems AH500 or AH502SD Central Warning Panel annunciators, it functions as a consolidating Master Caution/ Master Warning indicator and new alert acknowledge/voice mute switch as well as providing automatic dimming for night operation.

The unit measures 0.88in (22.2mm) square and has a panel depth of 2.4in (61mm) as detailed in the attached specification sheet. Captions are direct sunlight-readable, and supplied in both positive text (black text on illuminated background) and negative text (illuminated legend text on black).

The LEDs are high brightness and can be wired to PWM dimming, constant current or directly to 14V or 28V power with built in current limiting. The snap action momentary switch has double pole double throw connections. * These require special fit captions and logic. For details, Email: Click here or call for pricing.
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  • Full direct-daylight readable display
  • Hidden-until-lit captions
  • Automatic variable dimming (when combined with AH500 and AH501)
  • Suitable for 50mA PWM constant current drive
  • Suitable for 13.5V direct drive
  • Triple-redundant high-MTBF LED arrays
  • DPDT momentary snap action switch
  • Aviation Red and Yellow
  • Lightweight, compact and easy to install
  • High quality design and construction
  • 2-year warranty


AH501 Master Caution

  • V LED Positive input
  • Warning LED array PWM current sink
  • Caution LED array PWM current sink
  • Warning LED array current limited sink (for 13.5V)
  • Caution LED array current limited sink (for 13.5V)
  • 6 terminals for DPDT switch terminals
  • 1 Master Warning Aviation Red Caption
  • 1 Master Caution Aviation Yellow Caption
  • Hidden until lit
  • Full daylight readability
  • Non-reflective coating
  • Switch rated to 30 volts DC/ 12 volts AC, 2A resistive, 0.5A inductive
  • Maximum 50mA per illuminated legend
  • 100,000 cycles minimum
  • 0.2 (4.5mm) travel at 2Ibs +/- 1Ibs (908g +/- 454g)
  • Plastic enclosure
  • 0.745 by 0.645 by 3.14 (19 x 16 x 80 mm)
  • Weight 0.8oz (28g)
  • Operating Temperature: -30 to +50 deg C (-22F to 122F)
  • Storage Temperature: -50C to 80C (-58F to 176F)
  • Humidity: <85% non-condensing
  • Vibration: 10-2000Hz (20g)


  • Ever missed something important in your cockpit checks or scan that could have put you in danger? With the ever-increasing pressures of flying in busy airspace, it's too easy to do. Military and commercial aircraft have sophisticated monitoring and warning systems which watch the pilot's back while he or she focuses on demanding flight tasks where 100% attention is required, inside or outside the cockpit. In light-sports aircraft or experimentals, system monitors and cockpit warnings are often a mixed bag of individual warning lights or indicators scattered around the cockpit where they happen to fit. And while flat-screen displays can show a multitude of systems data and warnings, these are often densely packed and over-complex and abnormalities are easy to miss. And what about those situations where your early attention might avert a worse one developing? An actual fire might be difficult to miss, but what about high oil temperature or CHT, being in the wrong configuration or over speed, or fuel or oil running low, or low volts or vacuum? Might it be helpful too to be prompted to put your pitot heat on when icing becomes a threat, or to put your oxygen on as cabin pressure falls? Depending on your aircraft type, there will be other potential killers that could sneak up on you unnoticed. You've spent a lot on your machine, so spending just a little more for a system that alerts you when things need attention and helps to keep you and those with you safe, makes good sense. Any examination of FAA accident reports illustrates the point well: even the most experienced professional pilot can mess up! So we part-time, low-flight-hour aces might just need a bit of extra help.

In The Box

  • AH501 Master Warning/ Master Caution
  • Installation Manual



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: Does this unit work as an annunciator for the Garmin GI275 EIS?

Per the manufacturer, yes, it will work with Garmin products.

Q: Will this work with Electronics international MVP50?

No, it is not made for that system.

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