AD 2021-10-17 Requires Inspecting The Alternator Main Power Cable And The Exhaust Crossover Tube For Damage

The FAA is adopting a new airworthiness directive (AD) for certain Mooney International Corporation (Mooney) Model M20V airplanes.

This AD was prompted by reports of short circuit and arcing of the alternator main power cable in the engine compartment. This condition, if unaddressed, could result in a fire hazard, loss of engine thrust control, and reduced control of the airplane. This AD requires inspecting the alternator main power cable and the exhaust crossover tube for damage, replacing damaged parts as necessary, and installing an additional alternator cable clamp. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective July 7, 2021.

Supplementary Information: The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain serial-numbered Mooney Model M20V airplanes. The NPRM published in the Federal Register on March 9, 2021 (86 FR 13502; corrected March 17, 2021, 86 FR 14554). The NPRM was prompted by reports of short circuit and arcing of the alternator main power cable in the engine compartment.

Mooney determined the alternator main power cable was incorrectly positioned with slack in the cable and allowed contact between the alternator main power cable and turbocharger right-hand (RH) exhaust crossover tube. In one instance, this contact caused arcing of the alternator main power cable and created a hole in the RH exhaust crossover tube, which may result in a fire hazard. A damaged crossover tube may also decrease effectiveness of the turbochargers and cause complete loss of engine power at higher altitudes (above 9,000 ft. above sea level). In the NPRM, the FAA proposed to require inspecting the alternator main power cable and the exhaust crossover tube and modifying the alternator main power cable routing by installing an additional alternator cable clamp, part number (P/N) MS21919WCJ6. This condition, if not addressed, could result in an inflight fire and loss of engine thrust control, which may lead to reduced control of the airplane. The FAA is issuing this AD to address the unsafe condition on these products.

FMI: www.regulations.gov