Federal Aviation Administration February 14, 2012 – Federal Register Recent Federal Regulation Documents

We propose to adopt a new airworthiness directive (AD) for all Fokker Services B.V. Model F.28 Mark 0070 and 0100 airplanes. This proposed AD was prompted by an in-flight failure of the hydraulic control panel, which resulted in the absence of pressure and quantity indication of the hydraulic system and accompanying alerts for ``hydraulic system 1 low quantity'' and ``hydraulic system 2 low quantity.'' This proposed AD would require implementing new abnormal procedures for hydraulics in the airplane flight manual (AFM). We are proposing this AD to prevent loss of control of the airplane due to incorrect hydraulic system failure information being provided to the flightcrew, followed by application of inappropriate procedures.

We are superseding an existing airworthiness directive (AD) for all Turbomeca S.A. Arriel 2B and 2B1 turboshaft engines. That AD currently requires checking the transmissible torque between the low- pressure (LP) pump impeller and the high-pressure (HP) pump shaft on high-pressure/low-pressure (HP/LP) pump hydro-mechanical metering units (HMUs) that do not incorporate Modification TU 147. This new AD requires inspection and possible replacement of the HMU. This AD was prompted by three additional cases of uncoupling of the HP/LP pump HMU LP fuel pump impeller and the HP fuel pump shaft, since the existing AD was issued. We are issuing this AD to prevent an uncommanded in-flight shutdown, which can result in a forced autorotation landing or accident.