Airworthiness Directive · Amendment 39-11624 · AlliedSignal Inc. ALF502 and LF507 Series Turbofan Engines
AlliedSignal Inc. ALF502 and LF507 Series Turbofan Engines
Allied Signal Inc. (formerly Textron
Lycoming and Avco Lycoming) ALF502 and LF507 series turbofan engines, installed on but not limited to British Aerospace BAe 146-100A, BAe 146-200A, BAe 146-300A, AVRO 146-RJ70A,
AVRO 146-RJ85A, AVRO 146-RJ100A, and Canadair Model CL-600-1A11 series airplanes.
Note 1: This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (h) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This amendment supersedes two existing airworthiness directives (AD's), applicable to AlliedSignal Inc. ALF502 and LF507 series turbofan engines, that require rework or replacement of No. 4 and 5 bearing oil system hardware, initial and repetitive inspections of the oil system, optional installation of an improved oil filter bypass valve, and repetitive inspection of No. 4 and 5 bearing oil inlet tube, to ensure the integrity of the reduction gear system and overspeed protection system. This action would require replacement of the existing power turbine bearing housing assembly with a new, improved power turbine bearing housing assembly, and installation of a reworked or modified fourth turbine rotor disk assembly as a part of a design change to the new No. 4 bearing configuration that eliminates the requirement for repetitive inspections of oil system and No. 4 and 5 bearing oil inlet tube assembly. This amendment is prompted by one report of a contained power turbine rotor shaft separation forward of the Stage 4 low pressure turbine (LPT) rotor on an AlliedSignal Inc. ALF502R-5 engine. The LPT failure was caused by improper inspection of the engine oil system required by AD 97-05-11 R1. The actions specified by this AD are intended to prevent a No. 4 and 5 duplex bearing failure, which can result in a Stage 4 LPT rotor failure, an uncontained engine failure, and damage to the airplane.
(a) For AlliedSignal Inc. (formerly Textron Lycoming and Avco Lycoming) ALF502L and ALF502L2 series engines, prior to further flight, rework or replace the following parts and reassemble in accordance with Avco Lycoming Service Bulletin (SB) No. ALF502-72-0008, Revision 1, dated October 14, 1980, and SB No. ALF502-72-0010, dated October 14, 1980:
(1) Remove No. 4 and 5 bearing inlet tube assembly, part number (PN) 2-141-380-07/-08/-11/-12 and replace with PN 2-141-380-13/-14.
(2) Remove adapter assembly, PN 2-141-640-01 and replace with PN 2-141-640-02.
(3) If not previously incorporated, install Bracket, PN 2-143-049-01, spacer PN 2-143-051-01, two bolts PN STD3061-11, Clamp PN TA1501H05, Bolt PN MS9565-06, Nut PN STD3073-3, and Washer PN STD3035C2.
(4) Rework fourth stage turbine nozzle, PN 2-141-150-38, to PN 2-141-150-42, or PN 2-141-150-39 to PN 2-141-150-41 in accordance with SB No. ALF502-72-0010.
(5) Rework upper half of fire shield, PN 2-163-990-04 to 2-163-990-07, or PN 2-163-990-05 to 2-163-990-08 in accordance with SB No. ALF502-72-0010.
(6) Install: Washer, PN 2-163-585-01, and Spring PN 2-163-586-01, and Retainer PN 2-163-584-01.
(7) Remove oil feed line, PN 2-173-240-02 and replace with PN 2-303-377-01.
(8) Remove jam nut, PN R44118P05W. (The function of the jam nut is accomplished by the parts in paragraphs (a)(6) and (a)(7) of this AD.)
(9) Remove oil inlet support bracket, PN 2-141-335-02 and replace with PN 2-141-335-03.
(b) After replacement of the No. 4 and 5 bearing oil inlet tube and associated hardware in accordance with paragraph (a) of this AD, inspect the No. 4 and 5 bearing oil inlet tube at intervals not to exceed 100 hours time in service (TIS) since last inspection for chafing, in accordance with Avco Lycoming SB No. ALF502-72-0008, Revision 1, dated October 14, 1980. Prior to further flight, replace oil inlet tubes that exhibit chafing in excess of 0.010 inch deep with serviceable parts.
(c) For ALF502R series engines equipped with oil filter bypass valve, PN 2-303-432-01, accomplish the following:
(1) Inspect the engine oil filter bypass valve for leakage within the next 25 hours TIS or 25 flights in service, whichever occurs first, from the effective date of this AD, in accordance with Avco Lycoming Textron SB No. ALF 502R-79-0162, Original, dated March 23, 1987, or Revision 1, dated May 26, 1987. Prior to further flight, remove from service oil filters exhibiting any leakage and replace with serviceable parts.
(2) Thereafter, inspect the oil filter bypass valve for any leakage in accordance with Avco Lycoming Textron SB No. ALF 502R-79-0162, Original, dated March 23, 1987, or Revision 1, dated May 26, 1987, at intervals not to exceed 50 hours TIS or 50 flights in service since last inspection, whichever occurs first, and at the same time accomplish the following:
(i) Visually inspect the following engine chip detectors for metal contamination:
(A) For engines with a full flow chip detector installed, inspect the full flow chip detector.
(B) For engines without a full flow chip detector installed, inspect the chip detectors located in the accessory gearbox, Number 2 bearing scavenge line, and No. 4 and 5 bearing scavenge line.
(ii) For engines with engine chip detectors exhibiting Condition 3, or Condition 2, or Condition 1 where the oil filter bypass indicator is extended, prior to further flight, remove oil filter bypass valves exhibiting any leakage and replace with a serviceable part.
Note 2: Chip detector conditions are described in Figures 1, 2 and 3 of Avco Lycoming Textron SB No. ALF 502R-72-0160, Revision 1, dated March 23, 1987, or Revision 2, dated May 26, 1987.
(3) At the next engine shop visit, or within 2,500 hours TIS after the effective date of this AD, whichever occurs first, conduct the oil filter bypass valve spring compression force check, in accordance with Avco Lycoming Textron SB No. ALF 502R-79-0162, Original, dated March 23, 1987. Oil filter bypass valves that do not comply with the spring compression force limits contained in Avco Lycoming Textron SB No. ALF502R-79-0162, Original, dated March 23, 1987, must be removed and replaced with oil filter bypass valve, PN 2-303-432-02. Replacement of oil filter bypass valve, PN 2-303-432-01, with the improved oil filter bypass valve, PN 2-303-432-02, constitutes terminating action for the inspection requirements of paragraphs (c)(1) and (c)(2) of this AD.
(4) For the purpose of this AD, an engine shop visit is defined as engine maintenance that entails any of the following:
(i) Separation of a major engine flange (lettered or numbered) other than flanges mating with major sections of the nacelle reverser. Separation of flanges purely for purposes of shipment, without subsequent internal maintenance, is not a “shop visit.”
(ii) Removal of a disk, hub, or spool.
(iii) Removal of the fuel nozzles.
(d) For ALF502R, ALF502L, LF507-1F, and LF507-1H series engines, equipped with the No. 4 and 5 duplex bearing assembly numbers 2-141-930-01, 2-141-930-02, or 2-141-930-03, perform the repetitive oil system maintenance and inspections in accordance with the intervals and procedures described in the Accomplishment Instructions paragraphs of the applicable AlliedSignal Inc. SBs referenced in paragraphs (d)(1), (d)(2), (d)(3), and (d)(4) of this AD, within the next 25 hours TIS or 25 flights in service, whichever occurs first, from the effective date of this AD.
(1) For ALF502R series engines, in accordance with AlliedSignal Inc. SB No. ALF502R 79-9, Revision 1, dated November 27, 1996.
(2) For ALF502L series engines, in accordance with AlliedSignal Inc. SB No. ALF502L 79-0171, Revision 1, dated November 27, 1996.
(3) For LF507-1F series engines, in accordance with AlliedSignal Inc. SB No. LF507-1F-79-5, Revision 1, dated November 27, 1996.
(4) For LF507-1H series engines, in accordance with AlliedSignal SB No. LF507-1H-79-5, Revision 1, dated November 27, 1996.
(e) Modify the fourth turbine rotor disk assembly at the next access to the No. 4 and 5 duplex bearing assembly during the engine shop visit not to exceed 6,000 cycles in service (CIS) or 6,000 hours TIS, whichever occurs first, from the effective date of this AD, in accordance with the accomplishment instructions paragraph of AlliedSignal Inc. SB No. ALF/LF 72-1030, Revision 2, dated December 14, 1998.
(f) Modify the power turbine bearing housing assembly at the next access to the No. 4 and 5 duplex bearing assembly during the engine shop visit not to exceed 6,000 CIS or 6,000 hours TIS, whichever occurs first, from the effective date of this AD, in accordance with the accomplishment instructions paragraph of AlliedSignal Inc. SB No. ALF/LF 72-1040, Revision 1, dated December 14, 1998.
(g) Performance of the modifications described in paragraphs (e) and (f) of this AD constitutes terminating action to the rework and replacement requirements of paragraph (a), and the repetitive inspection requirements of paragraphs (b), (c), and (d) of this AD.
Note 3: Installation of a reworked or modified fourth turbine rotor disk assembly as a part of a design change to the new No. 4 bearing configuration that eliminates the requirements for repetitive inspections of oil system does not relieve the operators from accomplishment of the engine oil system inspection in accordance with the engine manufacturer's applicable maintenance documents.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Engines
