Federal Aviation Administration March 13, 2008 – Federal Register Recent Federal Regulation Documents

This document proposes adopting a new airworthiness directive (AD) for MD Helicopters, Inc. (MDHI) Model 369A, OH-6A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, and 369HS helicopters. The proposed AD would require repetitive tap inspections of each tail rotor (T/R) blade abrasion strip. This proposal is prompted by an incident in which an abrasion strip separated from a T/R blade. The actions specified by the proposed AD are intended to prevent disbonding and subsequent separation of an abrasion strip from a T/R blade, which could result in vibration, loss of the T/R, and subsequent loss of control of the helicopter.

The FAA is revising an earlier NPRM for an airworthiness directive (AD) that applies to all Airbus Model A318, A319, A320, and A321 airplanes. The original NPRM would have superseded an existing AD that currently requires inspecting to determine the part number and serial number of the fuel tank boost pumps and, for airplanes with affected pumps, revising the airplane flight manual (AFM) and the FAA- approved maintenance program. The existing AD also provides for optional terminating action for compliance with the revisions to the AFM and the maintenance program. The original NPRM proposed to require modifying or replacing the fuel tank boost pumps, which would terminate the AFM limitations and the maintenance program revisions. The original NPRM resulted from a report that a fuel tank boost pump failed in service, due to a detached screw of the boost pump housing that created a short circuit between the stator and rotor of the boost pump motor and tripped a circuit breaker. This new action revises the original NPRM by excluding certain modified airplanes from the applicability, requiring the AFM/maintenance program revisions on additional airplanes, and requiring modification or replacement of additional fuel tank boost pumps. We are proposing this supplemental NPRM to prevent electrical arcing in the fuel tank boost pump motor, which, in the presence of a combustible air-fuel mixture in the pump, could result in an explosion and loss of the airplane.

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

The FAA proposes to supersede an existing airworthiness directive (AD) that applies to all Boeing Model 747-400, 747-400D, and 747-400F series airplanes. The existing AD currently requires reviewing airplane maintenance records, doing repetitive inspections for cracking of the yaw damper actuator portion of the upper and lower rudder power control modules (PCMs), replacing the PCMs if necessary, and reporting all airplane maintenance records review and inspection results to the manufacturer. This proposed AD would limit the applicability, reduce the initial inspection threshold and repetitive interval, remove the reporting requirement, and require installation of a secondary retention device for the yaw damper modulating piston. Installation of the secondary retention device would terminate the repetitive inspection requirements. This proposed AD results from additional reports of failure or cracking of the PCM manifold in the area of the yaw damper cavity endcap at intervals well below the initial inspection threshold of the existing AD. We are proposing this AD to prevent an uncommanded left rudder hardover in the event of cracking in the yaw damper actuator portion of the upper or lower rudder PCMs, and subsequent failure of the PCM manifold, which could result in increased pilot workload, and possible runway departure upon landing.

We are adopting a new airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) issued by the aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

We propose to adopt a new airworthiness directive (AD) for certain Cessna Aircraft Company (Cessna) Model 525 airplanes. This proposed AD would require you to inspect for missing firewall sealant between the aft firewall assembly and seal assembly; and, if you find that firewall sealant is missing, seal with firewall sealant between the aft firewall assembly and seal assembly. This proposed AD results from a report that firewall sealant may not have been applied between the aft firewall assembly and seal assembly during manufacture of certain Model 525 airplanes. We are proposing this AD to detect and correct missing firewall sealant between the aft firewall assembly and seal assembly, which could result in failure of the fire extinguishing system to prevent the spread of fire through the firewall gap. This failure could lead to an uncontrolled fire.

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: During maintenance water has been found in the elevator assembly. The unsafe condition is water or ice accumulating in the elevator assembly, which could result in corrosion and consequent reduced structural integrity of the flight control surface, or an unbalanced flight control surface. These conditions could result in reduced controllability of the airplane. The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.

We are adopting a new airworthiness directive (AD) for certain Boeing Model 757-200, -200PF, and -200CB series airplanes. This AD requires doing an ultrasound inspection for disbonded tear straps not mechanically fastened to the skin, and related investigative and corrective actions, if necessary. This AD results from reports indicating that bonded skin panels may not have been correctly anodized in phosphoric acid before the tear strap doubler was bonded to the skin. We are issuing this AD to detect and correct a weak bond between the skin and tear strap. Such disbonding could reduce the ability of the skin to resist cracks and could adversely affect the structural integrity of the airplane.