Federal Aviation Administration December 30, 2011 – Federal Register Recent Federal Regulation Documents

We propose to adopt a new airworthiness directive (AD) for certain Model 737 airplanes. This proposed AD would incorporate design changes to improve the reliability of the cabin altitude warning system by requiring installation of a redundant switch of the cabin altitude pressure, replacing the aural warning module (AWM) with a new or reworked AWM, changing certain wire bundles, and connecting certain previously capped and stowed wires, as necessary. This proposed AD, for certain airplanes, would also require modifying the instrument panels, installing light assemblies, modifying the wire bundles, and installing a new circuit breaker, as necessary. This proposed AD was prompted by a report of a lack of cabin pressurization event caused by the flightcrew not receiving an aural warning because of the failure of the cabin altitude pressure switch. We are proposing this AD to prevent failure of the flightcrew to recognize and react to a lack of cabin pressurization, which could result in incapacitation of the flightcrew due to hypoxia (lack of oxygen in the body), and consequent loss of control of the airplane.

We propose to adopt a new airworthiness directive (AD) for certain Cessna Aircraft Company Model 560XL airplanes. This proposed AD was prompted by reports of jammed or stiff rudder control due to water freezing on the rudder bias cables and pulleys of the stinger. This proposed AD would require modification of the drain installation of the tailcone stinger on the aft canted bulkhead, inspections for drain holes in the forward and aft frames, and modification of the drain holes. We are proposing this AD to prevent ice accumulation on the cables and pulleys of the stinger, which could result in jamming of the rudder and consequent reduced controllability of the airplane.

We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 777-200 and -300 series airplanes. This proposed AD was prompted by reports of cracked retract actuator fuse pins that can fail earlier than the previously determined safe life limit of the pins. A fractured retract actuator fuse pin can cause the main landing gear (MLG) to extend without restriction and attempt to lock into position under high dynamic loads. This proposed AD would require an inspection for the part number of the fuse pin, and replacement of the pin if necessary. We are proposing this AD to prevent structural damage to the side and drag brace lock assemblies, which could result in landing gear collapse during touchdown, rollout, or taxi.

We are revising an existing airworthiness directive (AD) for Thielert Aircraft Engines GmbH models TAE 125-02-99 and TAE 125-01 reciprocating engines. That AD currently requires replacing the existing rail pressure control valve with an improved rail pressure control valve. This new AD requires the same actions but relaxes the initial compliance time from within 100 flight hours to within 600 flight hours for TAE 125-01 reciprocating engines. This AD was prompted by the determination that our AD was inadvertently more restrictive than European Aviation Safety Agency AD 2008-0128. We are issuing this AD to prevent engine in-flight shutdown, possibly resulting in reduced control of the aircraft.

We are adopting a new airworthiness directive (AD) for certain Lockheed Martin Corporation/Lockheed Martin Aeronautics Company Model L-1011-385-1, L-1011-385-1-14, L-1011-385-1-15, and L-1011-385-3 airplanes. This AD was prompted by results from a damage tolerance analysis conducted by the manufacturer indicating that fatigue cracking could occur in wing rear spar and upper surface zones. This AD requires repetitive inspections for cracking of the wing rear spar and upper surface zones, and repair if necessary. We are issuing this AD to detect and correct such fatigue cracking, which could result in cracking that grows large enough to reduce the wing strength below certificated requirements and possibly cause fracture of the rear spar, resulting in extensive damage to the wing and possible fuel leaks.

We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. This AD was prompted by reports of excessive in- service wear damage of the thumbnail fairing edge seal, and of the panel rub strip and skin assembly of the fan cowl. This AD requires replacement of the thumbnail fairing edge seals on both sides of the engines with Nitronic 60 stainless steel alloy seals. We are issuing this AD to prevent failure of the fire seal, which could allow a fire in the fan compartment to spread beyond the firewall and reach the flammable fluid leakage zones, resulting in an uncontrolled fire.