AD 95-01-05 Airworthiness Directives; Boeing Model 757 Equipped With Pratt & Whitney Model PW2000 Series Engines

Models named: 757 series, PW2000 series. Read the applicability below — it usually turns on serial or part numbers too.

Model 757 series airplanes equipped with Pratt & Whitney Model PW2000 series engines, certificated in any category.

Required as indicated, unless accomplished previously. To prevent damage to these engines due to ice ingestion into the compressor, which may result in the loss of power from the affected engine, accomplish the following: (a) Within 14 days after the effective date of this AD, revise the Limitations Section, Section 1, page 11, of the FAA-approved Airplane Flight Manual (AFM) to include the following statement. This may be accomplished by inserting a copy of this AD in the AFM. Ground Operations During Icing Conditions Periodic engine run-ups must be performed during prolonged ground operation in icing conditions (including time to taxi-in and taxi-out, and ground hold time), when engine anti-ice is required and the outside air temperature (OAT) is +3 degrees Centigrade (37 degrees Fahrenheit) or less. These momentary run-ups must be performed to a minimum of 50 percent N 1 in order to shed ice from the first stage of the low pressure compressor (LPC) stator. The run-up interval is established according to either paragraph a. or paragraph b., below: a. If a visual check of the leading edge of the first stage of the LPC stator has NOT been accomplished prior to engine start, run- ups must be performed at intervals not to exceed 15 minutes (including time to taxi-in and taxi-out, and ground hold time); or b. If a visual check of the leading edge of the first stage of the LPC stator has been accomplished prior to engine start and it is determined to be free of ice, run-ups must be performed at intervals not to exceed 30 minutes (including time to taxi-in and taxi-out, and ground hold time). Any ice accumulation on the first stage of the LPC must be removed prior to dispatch. In no case can the engines be operated for more than 30 minutes without either a visual check or an engine run-up. If either of the time limits in paragraph a. or paragraph b., above, is exceeded without performing a run-up, the aircraft must be taxied to an area where the engines can be shut down, a visual check for ice accumulation must be accomplished, and any ice must be removed prior to the next run-up or takeoff. During taxi to the area for the visual inspection, engine speeds greater than 40 percent N 1 should be avoided to minimize the potential for ice shedding into the engine compressor. If these requirements cannot be met, takeoff is not authorized. The procedures for accomplishing the visual check of and ice removal from the first stage of the LPC stator are contained in paragraphs (b) and (c) of AD 95-01-05. (b) Perform visual checks of the engine to detect ice build-up on the first stage of the LPC stator in accordance with the procedures specified in paragraphs (b)(1) and (b)(2) of this AD, at the times specified in the revision to the AFM required by paragraph (a) of this AD. These visual checks may be performed either by the cockpit flight crew or by certificated maintenance personnel. (1) Use adequate lighting to illuminate the first stage of the LPC stator. This stator can be viewed by standing at ground level, off to the side of the centerline of the engine, and viewing through the opening between the fan blades. (See Appendix 1, Figure 1 of this AD.) If ice is present, it will be seen to build up on the leading edge of the first stage of the LPC stator or the lip of the splitter. (See Appendix 1, Figure 2.) (2) This visual check is to be performed after engine shutdown. The visual check can be performed on a windmilling engine without bringing the fan rotor to a stop. It will actually become easier to see the first stage of the LPC stator if the rotor is turning. The ice will be visible, if present. (c) If any ice is detected on the first stage of the LPC stator (see Appendix 1, Figure 2) during the visual check required by paragraph (b) of this AD, it must be removed prior to dispatch of the aircraft, in accordance with the procedures specified in paragraph (c)(1) or (c)(2) of this AD, as applicable. [[Page 1714]] (1) If the total ground operating time since the last run-up to 50 percent N 1 is less than 30 minutes, the engine may be run-up to 50 percent N 1 to remove the ice, or it may be removed in accordance with the ``Ice Removal'' procedures described in paragraph (c)(2) of this AD. (2) If the total ground operating time since the last run-up to 50 percent N 1 is greater than 30 minutes, and the engine has been visually checked and it has been determined that ice has accumulated on the leading edge of the first stage of the LPC stator, the following ``Ice Removal'' (hot air de-icing) method must be used. Do not use hot water or aircraft de-icing fluids. Ice Removal De-ice the leading edge of the first stage of the LPC stator with the use of a suitable hot air source (e.g., heating cart). At no time should the temperature of the air supplied exceed 175 degrees Fahrenheit. Direct the air past the fan blades toward the first stage of the LPC stator. Continue hot air de-icing this LPC stator until all of the ice has been melted. Melted ice and ice chunks, which have been dislodged, should not be allowed to accumulate at the bottom of the fan duct where they could refreeze and become ingested into the engine during the next engine run-up. Note 1: The only acceptable means to remove ice from the first stage of the LPC stator are listed in paragraphs (c)(1) and (c)(2) of this AD. (d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Operations Inspector, who may add comments and then send it to the Manager, Seattle ACO. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. (e) This amendment becomes effective on January 20, 1995. BILLING CODE 4910-13-U [[Page 1715]] Appendix 1 [GRAPHIC][TIFF OMITTED]TR05JA95.001 BILLING CODE 4910-13-C [[Page 1716]] Issued in Renton, Washington, on December 27, 1994. James V. Devany, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 95-176 Filed 1-4-95; 8:45 am] BILLING CODE 4910-13-U