Narrative:

While performing an initial aircraft chkout, I (check pilot) asked the pilot I was evaluating to perform a no flap landing. To simulate the loss of hydraulic power and ensure proper landing gear extension with the emergency system, I turned off what I thought were simply hydraulic shutoff switches. I had performed this same task in another aeronautical commander that I'd been flying many times before, and have never seen any mention of wiring other than a simple direct connection from the hydraulic shutoff switches to the hydraulic shutoff valves. As I checked the hydraulic pressure and began bleeding off residual pressure, we experienced a loss of engine power. I immediately returned the switches that I'd thrown to the 'on' position. I advised the pilot being evaluated that I suspected that the switches were also wired to the fuel valves and that was the reason for the loss of power. As we verified the engine that had failed, the other engine failed as well. Not knowing why the engine power had not been restored by reversing the switches, I decided we should concentrate on making a safe forced landing. Both propellers were feathered and an uneventful landing on a highway near the airport was accomplished. When we investigated why the engines had quit, we found that the hydraulic and fuel shutoff valves were controled by the same switches, and that the switches had a placard 'emergency shutoff hydraulic and fuel control,' which was somewhat obscured by the switches themselves when viewing from the right seat. We also discovered that the switches would close the fuel and valves, but when the switches were turned back on, the fuel valves would not open unless the 3 position (open/off/closed) fuel valve switches were in the 'open' position. During this incident, the fuel switches had been in the 'off' position throughout the flight.

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Original NASA ASRS Text

Title: AN AERO COMMANDER 500B MADE AN OFF ARPT LNDG DUE TO INADVERTENTLY CLOSING BOTH ENG FUEL SHUTOFF VALVES.

Narrative: WHILE PERFORMING AN INITIAL ACFT CHKOUT, I (CHK PLT) ASKED THE PLT I WAS EVALUATING TO PERFORM A NO FLAP LNDG. TO SIMULATE THE LOSS OF HYD PWR AND ENSURE PROPER LNDG GEAR EXTENSION WITH THE EMER SYS, I TURNED OFF WHAT I THOUGHT WERE SIMPLY HYD SHUTOFF SWITCHES. I HAD PERFORMED THIS SAME TASK IN ANOTHER AERO COMMANDER THAT I'D BEEN FLYING MANY TIMES BEFORE, AND HAVE NEVER SEEN ANY MENTION OF WIRING OTHER THAN A SIMPLE DIRECT CONNECTION FROM THE HYD SHUTOFF SWITCHES TO THE HYD SHUTOFF VALVES. AS I CHKED THE HYD PRESSURE AND BEGAN BLEEDING OFF RESIDUAL PRESSURE, WE EXPERIENCED A LOSS OF ENG PWR. I IMMEDIATELY RETURNED THE SWITCHES THAT I'D THROWN TO THE 'ON' POS. I ADVISED THE PLT BEING EVALUATED THAT I SUSPECTED THAT THE SWITCHES WERE ALSO WIRED TO THE FUEL VALVES AND THAT WAS THE REASON FOR THE LOSS OF PWR. AS WE VERIFIED THE ENG THAT HAD FAILED, THE OTHER ENG FAILED AS WELL. NOT KNOWING WHY THE ENG PWR HAD NOT BEEN RESTORED BY REVERSING THE SWITCHES, I DECIDED WE SHOULD CONCENTRATE ON MAKING A SAFE FORCED LNDG. BOTH PROPS WERE FEATHERED AND AN UNEVENTFUL LNDG ON A HWY NEAR THE ARPT WAS ACCOMPLISHED. WHEN WE INVESTIGATED WHY THE ENGS HAD QUIT, WE FOUND THAT THE HYD AND FUEL SHUTOFF VALVES WERE CTLED BY THE SAME SWITCHES, AND THAT THE SWITCHES HAD A PLACARD 'EMER SHUTOFF HYD AND FUEL CTL,' WHICH WAS SOMEWHAT OBSCURED BY THE SWITCHES THEMSELVES WHEN VIEWING FROM THE R SEAT. WE ALSO DISCOVERED THAT THE SWITCHES WOULD CLOSE THE FUEL AND VALVES, BUT WHEN THE SWITCHES WERE TURNED BACK ON, THE FUEL VALVES WOULD NOT OPEN UNLESS THE 3 POS (OPEN/OFF/CLOSED) FUEL VALVE SWITCHES WERE IN THE 'OPEN' POS. DURING THIS INCIDENT, THE FUEL SWITCHES HAD BEEN IN THE 'OFF' POS THROUGHOUT THE FLT.

Data retrieved from NASA's ASRS site as of July 2007 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.