Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede an existing airworthiness directive (AD) for MD Helicopters Inc. (MDHI) Model 369A, 369D, 369E, 369H, 369HE, 369HM, 369HS, 369F and 369FF helicopters with certain MDHI or Helicopter Technology Company (HTC) tail rotor blades installed. The existing AD currently requires reducing the retirement life of each tail rotor blade (blade), performing a one-time visual inspection of each blade's pitch horn (pitch horn) for a crack or corrosion, and replacing any cracked blade or any blade that has exceeded its retirement life with an airworthy blade. The AD also requires reporting information to the FAA within 24 hours following the one-time inspection. Since we issued that AD, an accident in England prompted an investigation that showed corrosion on the blade's pitch horn that had not been detected under the paint. This proposed AD would retain some of the requirements in the existing AD but would require paint removal for all pitch horn inspections, inspecting for pitting and the shot peen surface's condition in addition to cracks and corrosion, and would add certain part-numbered blades to the applicability. The proposed actions are intended to prevent a pitch horn from cracking, leading to vibration, loss of tail rotor pitch control, and subsequent loss of tail rotor and helicopter control.