Summary
We propose to adopt a new airworthiness directive (AD) for certain M7 Aerospace LP SA226 and SA227 series airplanes. This proposed AD would require you to inspect electrical wires/components, hydraulic and bleed air tube assemblies at left-hand (LH) and right-hand (RH) inboard wing leading edge/battery box areas, LH/RH wing stations 51.167 to 81.174, and at all feed-through locations into the LH/RH inboard keelson. If chafing/arcing is found, this proposed AD would require you to reposition, repair, and/or replace all chafed electrical wires, components, and hydraulic and bleed air tube assemblies, as required. This proposed AD would also require you to reposition the battery lead cables, cover four-gauge wires leaving the battery box with firesleeving and secure with clamps, and protect the battery power cable. This proposed AD results from five reports of chafing between the bleed air tube and the electrical starter cables with one incident resulting in a fire. We are proposing this AD to detect and correct chafing/arcing of electrical wires, components, and bleed air lines. This condition could result in arcing of the exposed wires and burn a hole in the bleed air line or the nearby hydraulic line, and lead to a possible hydraulic fluid leak and fire in the engine nacelle compartment.