Emergency Airworthiness Directive. March 23, 2009 AD 2009-07-53.Sikorsky S-92.This Emergency Airworthiness Directive (AD) is prompted by the failure of two main gearbox filter bowl assembly mounting studs (studs) that were found broken during a fatal accident investigation in Canada. Prior to the accident, the manufacturer was investigating a July 2008 incident that also involved broken studs. In both cases, the broken studs resulted in rapid loss of oil. The failures have been tied to fretting and galling of the original titanium studs; therefore, we are requiring the removal of all titanium studs and replacement with steel studs. We are issuing this Emergency AD to prevent failure of a stud which could result in rapid loss of oil, failure of the main gearbox, and subsequent loss of control of the helicopter. We have reviewed Sikorsky Alert Service Bulletin No. 92-63-014A, Revision A, dated March 20, 2009, which describes procedures for removing the main gearbox bowl assembly titanium mounting studs and replacing them with steel mounting. This unsafe condition is likely to exist or develop on other helicopters of the same type design. Therefore, this AD requires, before further flight, replacing titanium studs with steel studs. The actions must be accomplished by following specified portions of the alert service bulletin described previously.

Airworthiness Directives; Boeing 737-300, -400, and -500. Final rule. SUMMARY: This AD requires repetitive high frequency eddy current inspections for cracking of the 1.04-inch nominal diameter wire penetration hole in the frame and frame reinforcement, between stringers S-20 and S-21, on both the left and right sides of the airplane and related investigative and corrective actions if necessary. This AD results from reports of cracking in the frame, or in the frame and frame reinforcement, common to the 1.04-inch nominal diameter wire penetration hole intended for wire routing. We are issuing this AD to detect and correct cracking in the fuselage frames and frame reinforcements, which could reduce the structural capability of the frames to sustain limit loads, and result in cracking in the fuselage skin and subsequent rapid depressurization of the airplane. This AD is effective April 15, 2009.

Airworthiness Directives; Bell Helicopter 412, 412CF, and 412EP. Final rule; request for comments. SUMMARY: This amendment adopts a new airworthiness directive (AD) for the specified Bell Helicopter Textron Inc. (Bell) model helicopters. This action requires reidentifying a certain part numbered main rotor yoke (yoke) based on whether it was ever installed on a Model 412CF helicopter or on a Model 412 or 412EP helicopter with a slope landing kit. This AD also requires reducing the retirement life of the reidentified yokes from 5,000 hours time-in-service (TIS) to 4,500 hours TIS. Also, this AD requires recording the reidentified yoke part number (P/N) and the reduced retirement life on the component history card or equivalent record. This amendment is prompted by fatigue analysis that shows that the retirement life should be reduced on certain yokes. The actions specified in this AD are intended to prevent fatigue cracking of a yoke, failure of a yoke, and subsequent loss of control of the helicopter. Effective March 31, 2009.

Airworthiness Directives; Cessna 208 and 208B. Final rule. SUMMARY: This AD requires you to modify the aileron carry-through cable attachment to the aileron upper quadrant with parts of improved design. This AD results from reports of a ''catch'' in the aileron control system when the control yoke is turned. We are issuing this AD to prevent the cable attach fitting on the aileron upper quadrant assembly from rotating and possibly contacting or interfering with the aileron lower quadrant assembly, which could result in limited roll control and reduced handling capabilities. This AD becomes effective on April 15, 2009.

Airworthiness Directives; Eurocopter EC 155B and EC155B1. Final rule; request for comments. SUMMARY: This AD results from mandatory continuing airworthiness information (MCAI) issued by the European Aviation Safety Agency (EASA), which isthe Technical Agent for the Member States of the European Community. The MCAI states that ''the Airworthiness Directive (AD) is prompted by the discovery of a short circuit evidence in hoist connector ''24 Delta'' even though the hoist was removed from the rotorcraft. The short circuit generated sufficient heat to ignite the paint on the cooler support cowling near the hoist cut-off connector ''24 Delta.'' This condition, if not corrected, could result in a fire in this area which could propagate to surrounding zones.'' This AD requires actions that are intended to address this unsafe condition. This AD becomes effective on March 31, 2009.

Airworthiness Directives; Boeing 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, and 747SP. Final rule. SUMMARY: This AD requires inspecting for skin cracks at the shear tie end fastener locations of the fuselage frames, and repairing cracks if necessary. This AD results from a widespread fatigue damage assessment of Model 747 airplanes. We are issuing this AD to detect and correct cracks in the fuselage skin that can propagate and grow, resulting in a loss of structural integrity and a sudden decompression of the airplane during flight. This AD is effective April 20, 2009.

Airworthiness Directives; Viking Air Limited Model DHC-7. Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for the products listed above. The 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: Transport Canada has received numerous service difficulty reports concerning Viking DHC-7 and Bombardier DHC-8 aircraft fluorescent lamp holder damage due to overheating. It has been determined that lamp holder overheating is a result of arcing between the fluorescent tube pins and the lamp holder contacts when the tube is not properly seated during installation. Overheating of lamp holders, if not corrected, could generate fumes and smoke. The unsafe condition could result in an in-flight fire. We are issuing this AD to require actions to correct the unsafe condition on these products. This AD becomes effective April 20, 2009.

Airworthiness Directives; Agusta AB139 and AW139. Final rule; request for comments. SUMMARY: This AD results from mandatory continuing airworthiness information (MCAI) issued by the European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community. The MCAI states: ''Operators had reported a number of occurrences of in-flight losses of cockpit door windows, both left and right side. This condition, if not corrected, could result in damage to critical components.'' The actions specified by this AD are intended to require that cockpit door windows (windows) be replaced with re-designed windows to prevent a window from separating from the helicopter, contacting the tailboom or tail rotor, resulting in loss of control of the helicopter. This AD becomes effective on March 31, 2009.

Airworthiness Directives; Bombardier CL-600-2B19 (Regional Jet Series 100 & 440. Final rule. SUMMARY: We are superseding an existing airworthiness directive (AD) for the products listed above. This 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 Bombardier CL-600-2B19 airplanes have had a history of flap failures at various positions for several years. Flap failure may result in a significant increase in required landing distances and higher fuel consumption than planned during a diversion. We are issuing this AD to require actions to correct the unsafe condition on these products. This AD becomes effective April 15, 2009.

Airworthiness Directives; Airbus A321-131 Final rule; request for comments. SUMMARY: This AD requires repetitive ultrasonic inspections to detect cracks in the wing inner rear spars at the attachment holes of the Main Landing Gear (MLG) forward pintle fitting, the actuator cylinder anchorage fitting, and rib 5 fitting; and repair of the sealant or repair of any crack. This AD results from a finding that certain A321-131 airplanes may not reach the design life goal due to differences in thickness of the inner rear spars and that fatigue cracks may develop on inner rear spars starting from the fastener holes for the attachment of gear rib 5, the forward pintle fitting, and the actuating cylinder anchorage on these airplanes. We are issuing this AD to detect and correct such fatigue cracks, which could result in reduced structural integrity of the airplane. This AD becomes effective March 31, 2009.

Airworthiness Directives; Fokker F.27 Mark 050. Final rule; request for comments. SUMMARY: This AD requires measuring the length of the extended portion of the sliding member of the main landing gear, performing an inspection for the presence of lock wiring, and doing corrective actions if necessary. This AD results from a report that the sliding member of the main landing gear has been overextended after landing. We are issuing this AD to detect and correct improper installation of the lock wire on the two lock bolts that hold the sliding member end stop, which could result in structural damage of the main gear and loss of control of the airplane during the landing roll, due to main landing gear overextension. This AD becomes effective March 31, 2009.