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A PA-31 on a maintenance flight returned to the departure airport when both alternators produced anomalous indications.
| Attributes | |
| ACN | 868970 |
| Time | |
| Date | 201001 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | PA-31 Navajo/Chieftan/Mojave/T1040 |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Cruise |
| Route In Use | None |
| Flight Plan | None |
| Component | |
| Aircraft Component | DC Regulator |
| Person 1 | |
| Function | Captain Pilot Flying Single Pilot |
| Qualification | Flight Crew Instrument Flight Crew Flight Instructor Flight Crew Commercial Flight Crew Multiengine |
| Experience | Flight Crew Last 90 Days 200 Flight Crew Total 2050 Flight Crew Type 730 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
I performed an engine run up. No abnormalities were noted during the run up. Then I took off and ATC advised me at 1000 MSL that they were not receiving my transponder. I recycled the transponder and ATC replied with the same response of 'not receiving your transponder.' I contacted our dispatcher and advised of the apparent inoperative transponder and I was instructed to return to the airport. When I was returning I noticed the voltmeter was reading 15 volts and there was a discharge. I switched to the auxiliary voltage regulator and normal charging resumed for about 30 seconds. At that point; I received a high voltage indication and the volts were reading 31 volts and above. I returned the voltage regulator switch to main and again received the discharge. I turned off my unneeded electrical equipment at this time. At this point approach instructed me to switch over to the tower who instructed me to enter a left base for runway 27R. About one minute later tower instructed me to make a right 360 turn for spacing and I reported that I had a dual alternator failure and requested to land as soon as practical. I was cleared to land #1 at this point. No further incidents occurred and the landing was uneventful.
Original NASA ASRS Text
Title: A PA-31 on a maintenance flight returned to the departure airport when both alternators produced anomalous indications.
Narrative: I performed an engine run up. No abnormalities were noted during the run up. Then I took off and ATC advised me at 1000 MSL that they were not receiving my transponder. I recycled the transponder and ATC replied with the same response of 'not receiving your transponder.' I contacted our Dispatcher and advised of the apparent inoperative transponder and I was instructed to return to the airport. When I was returning I noticed the voltmeter was reading 15 volts and there was a discharge. I switched to the auxiliary voltage regulator and normal charging resumed for about 30 seconds. At that point; I received a High Voltage indication and the Volts were reading 31 volts and above. I returned the voltage regulator switch to main and again received the discharge. I turned off my unneeded electrical equipment at this time. At this point Approach instructed me to switch over to the Tower who instructed me to enter a left base for Runway 27R. About one minute later Tower instructed me to make a right 360 turn for spacing and I reported that I had a dual alternator failure and requested to land as soon as practical. I was cleared to land #1 at this point. No further incidents occurred and the landing was uneventful.
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.