Federal Aviation Administration April 21, 2006 – Federal Register Recent Federal Regulation Documents

The FAA proposes to adopt a new airworthiness directive (AD) for certain Airbus Model A330-200 and -300, and A340-200 and -300 series airplanes. This proposed AD would require modifying certain rotary actuator assemblies for the leading edge slat. This proposed AD results from a leak found at the seal of the torque limiter output shaft of the Type A rotary actuator of leading edge slat No. 1. We are proposing this AD to prevent a decrease in the torque limiter function, which could result in degradation and damage to the attachment bolts of the leading edge slat, loss of the slat, and consequent reduced control of the airplane.

We propose to supersede Airworthiness Directive (AD) 98-12-01, which applies to certain Pilatus Aircraft Ltd (Pilatus) Models PC-6, PC-6/A, PC-6/B, and PC-6/C series airplanes equipped with turbo-prop engines. AD 98-12-01 currently requires you to modify the fuel system to improve the venting between the collector tank, the main wing tanks, and the engine. Since we issued AD 98-12-01, the FAA determined the action should also apply to all the models of the PC-6 airplanes listed in the type certification data sheet of Type Certificate (TC) No. 7A15 that are produced in the United States through a licensing agreement between Pilatus and Fairchild Republic Company (also identified as Fairchild Industries, Fairchild Heli Porter, or Fairchild-Hiller Corporation). In addition, the intent of the applicability of AD 98-12- 01 was to apply to affected serial numbers of the airplane models listed in TC No. 7A15. Consequently, this proposed AD would retain all the actions of AD 98-12-01, would add those Fairchild Republic Company airplanes to the applicability of this proposed AD, and would list out the individual specific airplane models. We are proposing this AD to prevent engine fuel starvation during maximum climb and descent caused by poor fuel tank venting with low fuel levels, which could result in a loss of engine power during critical phases of flight.

The FAA is superseding an existing airworthiness directive (AD), which applies to certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. That AD currently requires repetitive detailed and ultrasonic inspections of the thrust links of the rear engine mounts for any crack or fracture and corrective actions if necessary. This new AD requires repetitive replacement of the thrust links with new or overhauled thrust links, which ends the repetitive detailed and ultrasonic inspections. This AD results from the finding of fractured and cracked forward lugs of the rear engine mount thrust link on the number one strut on two airplanes. We are issuing this AD to prevent cracked or fractured thrust links that could lead to the loss of the load path for the rear engine mount bulkhead and damage to other primary engine mount structure, which could result in the in-flight separation of the engine from the airplane and consequent loss of control of the airplane.

This action would require holders of design approvals to make available to operators damage tolerance data for repairs and alterations to fatigue critical airplane structure. This proposal is needed to support operator compliance with the requirement to include damage tolerance inspections and procedures in their maintenance programs, and to enable operators to take into account the possible adverse effects of repairs and alterations on fatigue critical structure. The intended effect of this proposal is to ensure the continued airworthiness of fatigue critical airplane structure by requiring design approval holders to support operator compliance with specified damage tolerance requirements.