Airworthiness Directives; MD Helicopters, Inc., Helicopters
We are superseding Airworthiness Directive (AD) 2003-08-51 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. AD 2003-08-51 required 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. AD 2003-08-51 also required reporting information to the FAA within 24 hours following the one-time inspection. Since we issued AD 2003-08-51, 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 new AD retains some of the requirements of AD 2003-08-51 and also requires paint removal for all pitch horn inspections, inspecting for pitting and the shot peen surface's condition in addition to cracks and corrosion, and adds certain part- numbered blades to the applicability. These 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.