Federal Aviation Administration January 3, 2008 – Federal Register Recent Federal Regulation Documents

This notice contains a summary of a petition seeking relief from specified requirements of 14 CFR. The purpose of this notice is to improve the public's awareness of, and participation in, this aspect of FAA's regulatory activities. Neither publication of this notice nor the inclusion or omission of information in the summary is intended to affect the legal status of the petition or its final disposition.

This notice contains a summary of a petition seeking relief from specified requirements of 14 CFR. The purpose of this notice is to improve the public's awareness of, and participation in, this aspect of FAA's regulatory activities. Neither publication of this notice nor the inclusion or omission of information in the summary is intended to affect the legal status of the petition or its final disposition.

The FAA is adopting a new airworthiness directive (AD) for PW PW4164, PW4168, and PW4168A turbofan engines with certain low pressure turbine (LPT) stage 4 disks, part number (P/N) 51N404, installed. This AD requires removing certain LPT stage 4 disks, listed by serial number at the next piece-part exposure or within 7,500 cycles-since-new (CSN). This AD results from a report of improperly manufactured LPT stage 4 disks. We are issuing this AD to prevent an uncontained engine failure due to low-cycle fatigue (LCF), which could result in damage to the airplane.

This amendment adopts a new airworthiness directive (AD) for the specified Robinson Helicopter Company (Robinson) helicopters. This action requires a one-time visual inspection for skin separation along the leading edge of blade skin aft of the skin-to-spar bond line on the lower surface of each blade and in the tip cap area. This action also requires a ``tap test'' for detecting a separation or void in both bonded areas. This action also requires repainting any exposed area of the blades. If any separation or void is detected, replacing the blade before further flight is required. Thereafter, before each flight, this AD also requires checking for any exposed (bare metal) along the skin-to-spar bond line on the lower surface of each blade near the tip. If any bare metal is found, a mechanic must inspect the area. This amendment is prompted by 11 reports of blade debond, some occurring in flight causing the pilot to feel excessive vibrations and land, and some found during routine maintenance. The actions specified in this AD are intended to detect blade skin debond and to prevent blade failure and subsequent loss of control of the helicopter.

We are adopting a new airworthiness directive (AD) for certain Cessna Model 680 airplanes. This AD requires inspecting the routing of the aft fairing wire bundle assembly for adequate separation between the wiring and the hydraulic line; inspecting for chafing or damage of the wire bundle assembly and for damage to the hydraulic line, and doing corrective actions if necessary. This AD results from an incident report which indicated that a hydraulic leak and wire chafing, including signs of heat damage, were found within the lower tail cone fairing area. Similar wire chafing has also been found on other airplanes. We are issuing this AD to detect and correct wire chafing, and inadequate separation of the wiring and hydraulic line, which could lead to electrical arcing and a hydraulic leak and could result in a potential source of ignition and consequent fire.