PA-24 Comanche
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 167; Flight Crew Total 2163; Flight Crew Type 4
Situational Awareness; Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Diverted; Flight Crew Landed As Precaution; General Maintenance Action
Aircraft; Human Factors
I was assisting a friend (with a Private Pilot certificate) in acquiring a 1967 Comanche aircraft. Although he was appropriately rated and had the required endorsements; I would be the PIC for insurance purposes. The aircraft had been receiving annual inspections regularly; however; the airplane had been sitting for a number of years with little or no use. As such; an overhauled engine was to be installed as part of the sales arrangement. Additionally; other modifications to be completed prior to acquisition included: shoulder harness installation; improved stabilator horn and ADS-B transponder installation. When we arrived to pick up the aircraft; the engine cowling was laying on the floor; and much of the interior was still removed from the completion of previously-mentioned maintenance/modifications.Although slightly disappointed that the aircraft was not yet ready to fly (as had been promised by the FBO); the accessibility offered the opportunity to inspect the several areas of the aircraft; that would not have been possible otherwise (had the aircraft actually been closed up and 'ready' for flight at our arrival). Numerous items were found during our initial inspection; to include: throttle control not reaching the full travel stop at the engine; mixture control not reaching the full travel stop at the engine; intercom/radio system was unintelligible from the Captain's headset speaker; and the newly-installed transponder was powering up as soon as the master switch was selected on (it should be noted that the aircraft is not equipped with an avionics master). The Captain's headset speakerphone jack was found to have a cold solder joint; and was repaired; accordingly. Communication was tested between both pilot positions; and individually; to the control tower. Both engine control discrepancies were adjusted and corrected. The technician who installed the transponder explained that is was operating normally per the installation manual. I did not accept his explanation; however; I did not see this as a reason to refuse the aircraft; since it appeared to be working; as it was not an airworthiness issue. A test flight was conducted in the immediate airport area to ascertain the newly-installed engine performance and aircraft systems were in working order; and all was found to be acceptable. We decided to begin our 880 mile journey home. Less than hour into the flight at; we began to have difficulty hearing Center. Initially; I rationalized that must have been related to the repair that was made to the Captain's headset jack. Communications continued to diminish with Center. I felt that the radio issue was related to the speakerphone jack that was previously accomplished the day prior; and so I began to troubleshooting; accordingly. The headsets were swapped with no help. The spare boom mike was plugged in with no help. All attempts to bring the radio back were fruitless. My copilot was proactive and set up his portable radio in-line with the headset; and communication was then re-established with Center. We informed Center that we were having trouble with the radio; and we were going to make a precautionary landing at ZZZ; which was approximately 10 miles southeast of our location. Center told us to squawk VFR; and my copilot selected the VFR button on the transponder. I made a call to the local CTAF to announce our position/intention to land. I then looked to confirm the transponder was set to VFR; and found a 'Transponder Fail' message on the face of the unit. Consideration was giving to the recent history of maintenance with the speaker jack (and the previously-mentioned power issue to the transponder); I felt confident that we now had two separate issues that were related to the maintenance. When setting up to land; I called for the pre-landing check. When the gear was selected down; I witnessed the gear handle stop at half-travel from the floor; and took note that green light was not illuminated. It was then; that I realized we had an electrical system failure. I reached under the instrument panel and confirmed that the alternator field breaker was not tripped; but I did not call for the 'electrical failure' checklist. At this point; I felt the gear was a bigger issue (since it was stopped during half-travel). The manual extension procedure was carried out and the manual handle was moved to the full forward position. However; the green gear down light remained extinguished. Since the handle moved full travel forward (and felt like it over-centered into a positive detent); I would consider the gear to likely be down and locked. However; since the green light was not illuminated; a collective decision was made to treat the gear as if it was not fully locked in the down position; and prepare for the worst-case scenario. With the hand-held radio; I was able to contact the local FBO on Unicom; and I explained our situation. I requested them to have a look at our gear while we flew a low approach over the runway. They came back on the radio; and said that the gear appeared to be down. I requested them to locate the telephone number to the nearest fire department; and be ready to call them; should there be a gear collapse when we returned to land. Their response was in the affirmative; and that there was local Fire Department in the immediate vicinity of the airport.While flying the traffic pattern; I briefed my copilot; and we prepared for a gear collapse on touchdown. We landed without event and taxied to the ramp. During post-flight troubleshooting; the main circuit breaker (toggle switch under the panel) for the alternator was found tripped. The battery was charged and the main circuit breaker was reset. An engine run was performed and loading the electrical system could not duplicate the fault. The gear was reset; and the remainder of the trip was flown without event. In hindsight; I failed to recognize the electrical failure because of my bias toward the maintenance that had been performed. I became subject to tunnel-vision when suspecting the speaker phone jack repair was the cause of the radio issue. Had I properly identified the electrical failure at the time of the radio failure (prior to deciding on precautionary landing); the electrical system could have been reset and the gear would have been deployed normally; without event. All of the correct decisions are now crystal-clear; when evaluating from my desktop at home. However; at the time; I felt like we were doing the best we could with the sequence of events that occurred.
PA24 pilot reported electrical anomalies in cruise that he assumed were related to electrical issues that were repaired before flight and did not call for the 'electrical failure' checklist. The gear was extended manually and post flight revealed the main circuit breaker for the alternator was tripped.