Federal Aviation Administration December 4, 2012 – 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.

The FAA is revising a final rule published on June 7, 2000 (65 FR 36244). In that final rule, the FAA amended its regulations for the certification of changes to type-certificated products. That amendment was to enhance safety by applying the latest airworthiness standards, to the extent practical, for the certification of significant design changes of aircraft, aircraft engines, and propellers. The existing rule requires the applicant show that the ``changed product'' complies with applicable standards. This action revises that requirement so that an applicant is required to show compliance only for the change and areas affected by the change. The intended effect of this action is to make the regulation consistent with the FAA's intent and with the certification practice both before and after the adoption of the existing rule.

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 hydraulic fluid contamination found in the strut forward dry bay. This proposed AD would require repetitive general visual inspections of the strut forward dry bay for the presence of hydraulic fluid, and related investigative and corrective actions if necessary. We are proposing this AD to detect and correct hydraulic fluid contamination of the strut forward dry bay, which could result in hydrogen embrittlement of the titanium forward engine mount bulkhead fittings, and consequent inability of the fittings to carry engine loads, resulting in the loss or departure of an engine. Hydraulic embrittlement could cause a through-crack formation across the fittings through which an engine fire could breach into the strut, resulting in an uncontained strut fire.

We propose to supersede an existing airworthiness directive (AD) that applies to certain The Boeing Company Model 737-200, -200C, - 300, and -400 series airplanes. The existing AD currently requires repetitive inspections to detect cracking of the corners of the door frame and the cross beams of the aft cargo door, and corrective actions if necessary. The existing AD also requires a modification to the aft cargo door, which terminates the repetitive inspections. Since we issued that AD, we have received reports of cracking on doors on airplanes that were not included in the existing AD. This proposed AD would add airplanes to the applicability, add inspections and related investigative and corrective actions, and revise certain inspection types. This proposed AD would also reduce the compliance time, for certain doors, to do a modification of the doors. We are proposing this AD to prevent fatigue cracking of the corners of the door frame and the cross beams of the aft cargo door, which could result in rapid depressurization of the airplane.