Pilot regrets decision not to replace muffler
IFA Comment: The honest reflection post-incident does help other people. This was an airworthiness issue but a known one. An error was made. Talking about such incidents is key safety work
This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
I regret to inform you that while flying a Mooney M20C, I experienced a sudden and unexpected electrical failure.
As a result, all electrical systems on the aircraft ceased to function, including the cockpit instrumentation, lights, and radios. Additionally, smoke began to emanate from the cockpit, further complicating the situation.
In response to this situation, I immediately began the process of identifying a suitable landing site. After carefully assessing my options, I decided to return to the departure airport, as it was the closest and most familiar landing site available.
I was able to safely land the aircraft without incident.
Once on the ground, I immediately shut down the engine and evacuated the aircraft.
Subsequent examination after landing revealed that the intake air filter was on fire and, with the assistance from the people on the ground, I was given a fire extinguisher and put out the fire. The police were called and the fire department both responded to the incident.
The next day during daylight hours the airport fire department investigated the incident. A qualified fire official revealed faulty wiring as a possible root cause of the electrical failure.
I can assure you that I followed all appropriate procedures and acted with the utmost caution and professionalism throughout this incident.
For the safety of aviation and other people, I will tell you how the problem arose from poor maintenance.
Two days before the flight I was inspecting the muffler and left the cabin heater cover over the muffler loose. The fumes escaped from a hole in the muffler and started a fire on the cabin heating duct under the generator.
This engine is not very fuel efficient and a great amount of fuel vapor got out of the exhaust unburned. Unfortunately, it was discovered in flight where a rich mixture had been used during takeoff.
Contributing factors: A nice day for an early spring flight and forgetting about the muffler heating problem. The heater was not needed since it was a hot day.
Corrective actions are not needed because this item gets inspected during annual maintenance and you only see the hole on the muffler if you remove the heater cover over the muffler.
Human factors affecting the quality of the muffler: It is hard to get parts for this old airplane. I asked the maintenance facility on the field, which is a Mooney authorized repair station, for a muffler and they told me that I should remove my muffler and send it for repair. I asked why, I just wanted a new muffler. The IA said that this muffler will get shaped to the engine and a new muffler will cause problems. This misinformation caused me not to replace the muffler and caused this incident.
The electrical issue I noticed probably was caused by the fire under the generator.
The aircraft is not airworthy, and it looks like it is not going to be flying for a while. The actions not to replace the muffler caused the problem.