October 31, 2013 – Federal Register Recent Federal Regulation Documents

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 727 airplanes. This AD was prompted by certain mandated programs intended to support the airplane reaching its limit of validity (LOV) of the engineering data that support the established structural maintenance program. This AD requires, for certain airplanes, a modification of the web of the horizontal stabilizer center section rear spar. For the other airplanes, this AD requires an inspection for cracks in the web, and repair or modification as applicable. We are issuing this AD to prevent cracking at the upper fastener holes in the riveted web in the horizontal stabilizer center section rear spar, which could result in failure of the spar forging and lead to horizontal stabilizer separation and loss of control of the airplane.

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.

We are adopting a new airworthiness directive (AD) for certain Bell Model 430 helicopters. This AD requires installing a placard on the instrument panel and revising the limitations section of the rotorcraft flight manual (RFM). This AD was prompted by several incidents of third stage engine turbine wheel failures, which were caused by excessive vibrations at certain engine speeds during steady- state operations. These actions are intended to alert pilots to avoid certain engine speeds during steady-state operations, prevent failure of the third stage engine turbine, engine power loss, and subsequent loss of control of the helicopter.

We are adopting a new airworthiness directive (AD) for certain Bell Model 407 helicopters. This AD requires installing a placard beneath the NR/NP dual tachometer and revising the limitations section of the rotorcraft flight manual (RFM). This AD was prompted by several incidents of third stage engine turbine wheel failures, which were caused by excessive vibrations at certain engine speeds during steady- state operations. These actions are intended to alert pilots to avoid certain engine speeds during steady-state operations, prevent failure of the third stage engine turbine, engine power loss, and subsequent loss of control of the helicopter.