Federal Aviation Administration March 9, 2006 – Federal Register Recent Federal Regulation Documents

The FAA proposes to adopt a new airworthiness directive (AD) for Turbomeca Arriel 2B, 2B1, and 2B1A turboshaft engines. This proposed AD would require visually inspecting the splines of the high- pressure (HP) pump drive gear shaft and coupling shaft assembly for wear. This proposed AD results from reports of uncommanded in-flight shutdowns of engines. We are proposing this AD to detect wear on the splines of the HP pump drive gear shaft and coupling shaft assembly, which could interrupt the fuel flow and cause an uncommanded in-flight shutdown of the engine on a single-engine helicopter. The in-flight shutdown of the engine could result in a forced autorotation landing or accident.

This document makes a correction to Airworthiness Directive (AD) 2006-05-01. That AD applies to Rolls-Royce plc RB211 Trent 500, 700, and 800 series turbofan engines. We published AD 2006-05-01 in the Federal Register on March 1, 2006, (71 FR 10415). An incorrect engine model number exists in the compliance section, in two places. This document corrects the engine model number. In all other respects, the original document remains the same.

The FAA is superseding three existing airworthiness directives (ADs) that apply to certain Boeing Model 747 airplanes. The existing ADs currently require repetitive inspections of the body station (BS) 2598 bulkhead, and corrective action if necessary. This new AD adds a requirement to modify the bulkhead, including a one-time inspection and corrective action if necessary, which terminates certain repetitive inspections. This AD also requires a post-modification inspection of the modified area. This AD results from new reports of cracking in all three areas that require inspection in accordance with the existing ADs. We are issuing this AD to prevent fatigue cracking of the BS 2598 bulkhead structure, which could result in inability of the structure to carry horizontal stabilizer flight loads, and loss of controllability of the airplane.

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 747-200C, -200F, -400, -400D, and -400F series airplanes. This AD requires repetitive inspections for cracks in the overlapping (upper) skin, upper fastener row of the lap joints of the fuselage skin in sections 41, 42, and 46; and related investigative and corrective actions, if necessary. This AD results from fatigue tests and an analysis that identified areas of the fuselage lap joints where fatigue cracks can occur. We are issuing this AD to detect and correct fatigue cracks in the overlapping (upper) skin, upper fastener row of the lap joints of the fuselage skin in sections 41, 42, and 46, which could adversely affect the structural integrity of the airplane.