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An M20 pilot experienced a stall warning horn when the master switch was turned on with the aircraft on the ground. The stall warning circuit breaker was pulled and the reporter returned to home base. The anomaly cannot be reproduced when the circuit breaker is later reset.
| Attributes | |
| ACN | 957173 |
| Time | |
| Date | 201107 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Make Model Name | M-20 Series Undifferentiated or Other Model |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Parked |
| Flight Plan | None |
| Component | |
| Aircraft Component | Stall Warning System |
| Person 1 | |
| Function | Pilot Flying Single Pilot |
| Qualification | Flight Crew Commercial Flight Crew Multiengine Flight Crew Instrument |
| Experience | Flight Crew Last 90 Days 15 Flight Crew Total 865 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural FAR Flight Deck / Cabin / Aircraft Event Other / Unknown |
Narrative:
I flew to a nearby airport for dinner with some friends. It was a great flight over. Before my return flight; as expected; a storm passed over and it rained a decent amount. We finished up eating and; about twenty minutes later; the weather has cleared far enough for me to depart. I load up the airplane; master switch on. Next thing you know the overhead speaker is screeching like none other. I can't for the life of me think what it might be. It sounded much too shrill for the stall horn. It wasn't the autopilot. No switches changed it. The landing gear switch was in the down position. It wasn't the same tone as the gear warning. So I get out of the plane; leaving the master on and go activate the stall horn. Now there are two different horns going off in the airplane; so I know that it's not a stuck stall horn. Finally I get the idea to just start pulling circuit breakers to see what stops it. Sure enough; the stall circuit breaker ends the noise. So apparently I now have a stall horn that always stays on; and another that actually comes on when the stall switch is engaged. In my get-there-itis I took off without an operational stall horn (breaker pulled); entirely forgetting the fact that this is not legal. After resetting the circuit breaker later; I cannot recreate this fluke problem and have consulted my a&P for guidance.
Original NASA ASRS Text
Title: An M20 pilot experienced a stall warning horn when the master switch was turned on with the aircraft on the ground. The stall warning circuit breaker was pulled and the reporter returned to home base. The anomaly cannot be reproduced when the circuit breaker is later reset.
Narrative: I flew to a nearby airport for dinner with some friends. It was a great flight over. Before my return flight; as expected; a storm passed over and it rained a decent amount. We finished up eating and; about twenty minutes later; the weather has cleared far enough for me to depart. I load up the airplane; Master switch ON. Next thing you know the overhead speaker is screeching like none other. I can't for the life of me think what it might be. It sounded much too shrill for the stall horn. It wasn't the autopilot. No switches changed it. The landing gear switch was in the down position. It wasn't the same tone as the gear warning. So I get out of the plane; leaving the Master ON and go activate the stall horn. Now there are two different horns going off in the airplane; so I know that it's not a stuck stall horn. Finally I get the idea to just start pulling circuit breakers to see what stops it. Sure enough; the STALL circuit breaker ends the noise. So apparently I now have a stall horn that always stays on; and another that actually comes on when the stall switch is engaged. In my get-there-itis I took off without an operational stall horn (breaker pulled); entirely forgetting the fact that this is not legal. After resetting the circuit breaker later; I cannot recreate this fluke problem and have consulted my A&P for guidance.
Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.