Federal Aviation Administration October 19, 2007 – Federal Register Recent Federal Regulation Documents

This document proposes superseding an existing airworthiness directive (AD) for MD Helicopters, Inc. (MDHI) Model 600N helicopters. That AD currently requires interim initial and repetitive inspections of tailboom parts, installing six inspection holes in the aft fuselage skin panels, installing tailboom attachment bolt washers, modifying both access covers, and replacing broken attachment bolts. The current AD also provides for modifying the fuselage aft section as an optional terminating action. This proposal would mandate modifying the fuselage aft section within the next 24 months to strengthen the tailboom attachment fittings and upper longerons. The actions specified by the proposed AD are intended to prevent failure of the tailboom attachment fittings, separation of the tailboom from the helicopter, and subsequent loss of control of the helicopter.

We propose to supersede Airworthiness Directive (AD) 2007-13- 11, which applies to all Eclipse Aviation Corporation (Eclipse) Model EA500 airplanes. AD 2007-13-11 was prompted by reports of loss of primary airspeed indication due to freezing condensation within the pitot system. AD 2007-13-11 requires operational limitations consisting of operation only in day visual flight rules (VFR), allowing only a VFR flight plan, and maintaining operation with two pilots. Since we issued AD 2007-13-11, Eclipse has developed a design modification to the pitot/angle-of-attack (AOA) system to eliminate the possibility of freezing condensation within the pitot/AOA system. Eclipse is incorporating this modification during production on Model EA500 airplanes starting with serial number (S/N) 000065. Consequently, this proposed AD would limit the applicability to airplanes under S/N 000065 and require incorporating the modification. This proposed AD would also retain the operating limitations in AD 2007-13-11 until the modification is incorporated. We are proposing this AD to prevent long- term reliance on special operating limitations when a design change exists that would eliminate the need for the operating limitations. Incorporating the proposed modification would prevent loss of air pressure in the pitot system, which could cause erroneous AOA and airspeed information with consequent loss of control.