Narrative:

I am a flight instructor for a university flight school. During the run-up before a routine training flight; my student determined that the ammeter was not functioning properly. With the engine running at 1800 rpm; he turned the landing light on; but the ammeter did not show a slight; brief deflection; as it should have. Changing the flap setting had the same results. We called back to the dispatch office on the unicom frequency; and dispatch called the maintenance department. Mr. X; director of aircraft maintenance; and mr. Y assistant director of aircraft maintenance both drove to the run-up area to trouble-shoot the airplane. My student and I shut down the aircraft while we waited for them to arrive; and when they did; they started the aircraft; and checked the ammeter for themselves. I did not see first-hand what they did to check it; since the airplane doors were closed and my student and I were standing well away from the airplane. They both agreed that the ammeter was inoperative; and the three of us (mr. X; mr. Y; and myself) then proceeded to try to determine if the airplane could still be flown. The airplane does not have a minimum equipment list; and the ammeter is not required by 14 crash fire rescue equipment 91.205 or any airworthiness directives. We then proceeded to check the comprehensive equipment list in the airplane's operating handbook. All three of us reviewed the list multiple times; but were unable to find the ammeter anywhere on the list. The most closely related item we found was the ammeter transducer; located under the electrical power section. After searching the comprehensive equipment list at least 4 times; mr. X and mr. Y both assured me and my student that it was 'just a broken gauge' and that the airplane was airworthy. They encouraged us to monitor the voltmeter if we had any concerns about the functionality of the alternator; and stated several times that they had absolutely no doubts that the airplane was airworthy. They expressed surprise over the fact that the ammeter did not appear to be included on the comprehensive equipment list. Upon later examination; it was found that the ammeter is located in the comprehensive equipment list under the vacuum system. Had the ammeter been located in the electrical power system section; it would have been easily seen and the airplane would have been deemed not airworthy and would have never been flown.

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Original NASA ASRS Text

Title: A group of flight instructors and their students report flying an aircraft with an inoperative ammeter which was deemed airworthy at the time. It was later determined that the ammeter was a required piece of equipment.

Narrative: I am a flight instructor for a University flight school. During the run-up before a routine training flight; my student determined that the ammeter was not functioning properly. With the engine running at 1800 rpm; he turned the landing light on; but the ammeter did not show a slight; brief deflection; as it should have. Changing the flap setting had the same results. We called back to the dispatch office on the UNICOM frequency; and dispatch called the maintenance department. Mr. X; Director of Aircraft Maintenance; and Mr. Y Assistant Director of Aircraft Maintenance both drove to the run-up area to trouble-shoot the airplane. My student and I shut down the aircraft while we waited for them to arrive; and when they did; they started the aircraft; and checked the ammeter for themselves. I did not see first-hand what they did to check it; since the airplane doors were closed and my student and I were standing well away from the airplane. They both agreed that the ammeter was inoperative; and the three of us (Mr. X; Mr. Y; and myself) then proceeded to try to determine if the airplane could still be flown. The airplane does not have a Minimum Equipment List; and the ammeter is not required by 14 CFR 91.205 or any airworthiness directives. We then proceeded to check the Comprehensive Equipment List in the airplane's operating handbook. All three of us reviewed the list multiple times; but were unable to find the ammeter anywhere on the list. The most closely related item we found was the ammeter transducer; located under the Electrical Power section. After searching the Comprehensive Equipment List at least 4 times; Mr. X and Mr. Y both assured me and my student that it was 'just a broken gauge' and that the airplane was airworthy. They encouraged us to monitor the voltmeter if we had any concerns about the functionality of the alternator; and stated several times that they had absolutely no doubts that the airplane was airworthy. They expressed surprise over the fact that the ammeter did not appear to be included on the Comprehensive Equipment List. Upon later examination; it was found that the ammeter is located in the Comprehensive Equipment List under the Vacuum system. Had the ammeter been located in the Electrical Power system section; it would have been easily seen and the airplane would have been deemed not airworthy and would have never been flown.

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.