Guidelines for Reuse of Damaged Engines and Engine Parts [PW11]

TASK 70-50-00-910-801-A
Guidelines for Reuse of Damaged Engines and Engine Parts

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TASK 70-27-00-910-806-A	SPOP 425 - Requirements after Contact with Fire Extinguishing Agents, Hydraulic Fluid, Fuel or Oil

3. Job Set-up
Subtask 70-50-00-869-050-A ** ON A/C NOT FOR ALL

A. Not applicable.

4. Procedure
Subtask 70-50-00-910-050-A ** ON A/C NOT FOR ALL

A. General
(1) The subsequent guidelines are provided to assist owners, operators, and maintenance facilities in the disposition of engines and engine parts involved in abnormal operational circumstances.
(a) Abnormal operational circumstances are defined as accidents or other events which fall outside of the operating envelope for the engine, aircraft and/or the engine/aircraft combination as initially certified and where inspection, refurbishment, and repair data are not addressed by Transport Canada Civil Aviation (TCCA) approved publications (such as Engine Manuals and Service Bulletins).
(b) The data contained in these TCCA approved publications normally address engine and engine parts which experience wear, deterioration, or damage through exposure to the usual day-to-day operating environment.
(2) The guidelines apply to the engine-associated abnormal operational circumstances that follow:

NOTE: The guidelines refer to the abnormal operational circumstances of an engine or aircraft. It is important that the damage be identified as engine-caused or related to abnormal operation of the aircraft so correct application of the inspection guidelines can be made.

NOTE: The inspection guidelines are written for evaluation of suspected damage of an engine-induced abnormal operational circumstance (such as a major rotor failure). These guidelines take into account the loads generated by the engine.

NOTE: These inspection guidelines, however, may not sufficiently cover engines or parts that have been subjected to excessive external loads brought on by an abnormal operation of the aircraft (such as an aircraft landing accident where the engines are impacted). Evidence of excessive external loading generated by an aircraft abnormal operation will be found where external loads have been applied to major structural case/mounts or rotating elements that either result in the permanent distortion to the major load-carrying elements and/or the separation of a running engine from its attachments.

(a) Abnormal Operational Circumstances - Engines and Engine Parts Unacceptable for Continued Aircraft Use
(b) Abnormal Operational Circumstances - Engines and Engine Parts Potentially Acceptable for Continued Aircraft Use
(3) For abnormal operational circumstances not addressed by these guidelines, Pratt & Whitney considers engines and engine parts unacceptable for continued aircraft use unless reviewed and approved on a case-by-case basis.
(4) The guidelines are based upon Pratt & Whitney's general experience in this area and therefore are to be used as general guidelines. In any particular incident, however, more complete information or inspection results may require alternate action. The engine or engine part owner should not rely upon the information in these guidelines without a thorough understanding of the damage to the engine or engine parts and its effect on engine operation. "It should be understood that the following are only guidelines and that any and all responsibility for returning any engine or engine part to service remains with the engine or part owner".
(5) The definitions that follow are for technical terms from the ATA World Airlines Technical Operations Glossary (WATOG) used in these guidelines:
(a) Accident: An occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight, until such time as all such persons have disembarked, in which:
1 Any person suffers death or serious injury as a result of being in or upon the aircraft or by direct contact with the aircraft or anything attached thereto; or
2 The aircraft receives substantial damage or
3 Any damage is caused to the property of a third party.
(b) Damage, accidental: Physical deterioration of an item caused by contact or impact with an object or influence which is not a part of the aircraft, or by incorrect manufacturing or maintenance practices.
(6) The definitions that follow are for non-WATOG technical terms used in these guidelines:
(a) Engine: Engines made by Pratt & Whitney Division of United Technologies Corporation
(b) Engine Parts: Parts sold by Pratt & Whitney and delivered as original equipment in an engine installed on an airplane or installed in a spare engine or sold by Pratt & Whitney as new spare parts for an engine.

NOTE: Engine parts include vendor-supplied accessories and components which are approved by Pratt & Whitney.

(c) Abnormal Operational Circumstances: Accidents or other events which occur outside the operational envelope for the engine or the airplane or the engine and airplane combination as it was initially certified, and where inspection, refurbishment, and repair data are not in TCCA approved publications (such as Engine Manuals, Service Bulletins, etc.).

Subtask 70-50-00-910-051-A ** ON A/C NOT FOR ALL

B. Abnormal Operational Circumstances - Engines and Engine Parts Unacceptable for Continued Aircraft Use
(1) Pratt & Whitney considers engines and engine parts involved in the subsequent types of circumstances unacceptable for continued aircraft use:

NOTE: It is recognized that an aircraft could be damaged beyond economical repair without any resulting engine involvement. In such cases, the engine and engine parts can be considered "not involved" in an abnormal operational circumstance.

(a) Engines and engine parts installed in an aircraft totally destroyed by fire
(b) Engines and engine parts totally engulfed in fire to the extent that outer cases have been heat discolored and/or distorted or the engine is otherwise damaged by heat over a significant area of the engine, either external or internal
(c) Engine and engine parts installed in an aircraft totally destroyed by impact damage
(d) Evidence of excessive external loads generated by abnormal aircraft operation
(e) Engine or engine parts subjected to partial or full immersion in salt water.

Subtask 70-50-00-910-052-A ** ON A/C NOT FOR ALL

C. Abnormal Operational Circumstances - Engines and Engine Parts Potentially Acceptable for Continued Aircraft Use
(1) Accidents
(a) Pratt & Whitney considers engines and engine parts involved in the types of accidents that follow potentially acceptable for continued aircraft use:
1 Type 1: Engines and engine parts involved in an accident in which the nacelles and engines remain undamaged
2 Type 2: Engines or engine parts involved in a fire wherein a portion of the aircraft was destroyed but the engines were not subjected to fire damage
3 Type 3: Engines which will not rotate freely but do not exhibit evidence of being subjected to excessive external loads
4 Type 4: Engines subjected to partial or full immersion in fresh water for a brief period of time.
(b) Acceptance criteria for engines or engine parts:
1 Engines and engine parts involved in Type 1 and Type 2 accidents can be considered "not involved" in an abnormal operational circumstance.
2 Engines and engine parts involved in Type 3 and Type 4 accidents should be 100 percent disassembled and examined. Refer to the following paragraph, Accident Engine, General Inspection Guidelines for general guidelines to be used in conjunction with TCCA approved publications.

NOTE: Owners who are unable to do the necessary tests or in doubt whether to accept or reject a part should contact Pratt & Whitney for assistance.

Subtask 70-50-00-910-053-A ** ON A/C NOT FOR ALL

D. Serious Operational Events
(1) Pratt & Whitney considers engines and engine parts involved in the subsequent types of serious operational events as potentially acceptable for continued aircraft use if the criteria defined are observed:
(a) Single fan blade fractures more that XX inches from the blade root bottom

NOTE: A single fan blade fracture that occurs more that XX inches from the blade root bottom can cause varying degrees of engine damage. Refer to the specific AMM maintenance and inspection tasks for bird or object ingestion inspections and damage limits. In general, the inspection guidelines that follow can be applied to events where a single blade has fractured more that XX inches from the blade root bottom.

1 Check for evidence of core ingestion.
2 Examine the fan blade airfoils for surface damage, bends, curls and damage.
3 Examine the fan blade fairings for damage.
4 Check the inlet cone front and rear segment for damage.
5 Examine the fan rubstrip for damage beyond limits.
6 Check the fan exit guide vanes for damage.
7 Examine the engine externals for broken or cracked brackets and case flanges.
8 Do a borescope inspection of the compressor gaspath for excessive blade tip rub and blade-to-vane clash.
(b) Single blade fracture less than the allowable limits from the blade root bottom or multiple fan blade fractures

NOTE: A single fan blade fracture less than the allowable limits from the blade root bottom or multiple fractures generate a significant amount of rotor vibration. More extensive inspections with disassembly of the N1 rotor modules is necessary as a minimum. Further teardown is necessary as inspection findings dictate.

1 Scrap N1 rotor mainshaft bearings and N2 rotor mainshaft roller bearings.
2 Examine the N1 rotor shaft (front compressor turbine driveshaft) for rub with the N2 rotor shaft.
3 Examine cases, bearing supports, and fan ducts for distortion and cracks particularly at engine mount locations.
4 Examine the main oil filter and chip detectors.
5 Examine the gearbox mounts.
6 Examine all external components, tubing and wiring for cracks and chafing.
7 Do a visual and borescope inspection of modules not disassembled for object damage, excessive blade tip rub or blade-to-vane clash.
(c) Serious engine damage within modules or build groups from major rotating parts fractures
1 There is considerable variability in resultant damage from compressor and turbine blade fractures. As a minimum, the affected module requires teardown inspection. A thorough visual and borescope inspection of the modules not disassembled should be done. The modules should be disassembled if gaspath damage is noted or metal spatter is observed on hot section parts. If the blade fracture is determined to have resulted from object damage, then forward modules should be disassembled to access upstream damage and determine the source of damaging object.
2 Disk or spacer (rotating airseal) fractures usually result in significant damage. Moreover, the engine experiences high vibration as a result. In such events, a total engine teardown should be done. Special attention should be directed at shafts and cases for cracks and distortion.
(d) Serious engine damage within modules or build groups from major stationary parts fractures
1 The most significant stationary part fractures are usually associated with compressor stators. In past experience, HPC stator fractures have caused significant resultant damage. In most instances, serious overtemperature of hot section parts has occurred. A total teardown and inspection of the affected module is necessary. Examine disks for cracks, particularly in the blade slot/rim areas. Examine blades for cracks and damage. If metal spatter or evidence of overtemperature are observed on downstream module parts, disassemble and examine downstream modules. Examine all mainshaft bearings.
(e) Mainshaft bearing and gearbox distress
1 An engine which experiences a mainshaft bearing fracture must be disassembled sufficiently to examine the affected compartment area (this includes journal surfaces, compartment seals and scavenge pump). The gearbox, which includes the angle gearbox, should also be disassembled and examined since it is an integral part of the oil system where bearing debris can collect. If the affected compartment is drained through the gearbox drive (towershaft) system, disassemble and examine the drive system components.
2 For an engine which experiences shaft or bearing fracture in the gearbox drive (towershaft) system, disassemble and examine the gearbox drive system and the gearbox (this includes the angle gearbox).
3 A teardown and inspection of the gearbox and parts therein is all that is necessary if the distress is fully contained within the gearbox. However, if there is evidence of bearing, gear or spline distress, do a progressive inspection through the gearbox drive (towershaft) system until assured of no further distress.
(f) Engines which experience sudden stoppage
1 An engine experiences sudden stoppage usually as a result of significant ingestion or distress. In every instance of sudden stoppage, a total engine teardown and 100 percent engine part inspection should be done. During teardown, special attention should be paid to that which follows:
2 Examine all cases and bearing supports for distortion.
3 Examine the rotor shafts and hubs for twists and splines for wear and distortion.
4 Examine the mainshaft bearings and replace as necessary. Sudden stoppage interrupts oil flow which may cause heat soak to damage bearings. Scrap bearings that show heat discoloration.
(g) Engines involved in an operational fire (burnthrough, bearing compartment, etc.)
1 An engine involved in an operational fire should be fully torn down with subsequent inspection of all engine parts. Refer to the subsequent paragraph, Accident Engine, General Inspection Guidelines, for disposition of engine parts with particular attention to those that show heat discoloration.
2 If extinguishing agents have been applied to the engine, gaspath cleaning is to be done by the applicable of an AMM maintenance task, as quickly as practical, to prevent corrosion. Refer to Cleaning Requirements after Contact with Fire Extinguishing Agents, Hydraulic Fluid, Fuel, or Oil (SPOP 425) (Ref. AMM TASK 70-27-00-910-806).

Subtask 70-50-00-910-054-A ** ON A/C NOT FOR ALL

E. Impacted and Dropped Engines

NOTE: Refer to the previous paragraph, Abnormal Operational Circumstances - Engines and Engine Parts Unacceptable for Continued Aircraft Use, for engines impacted and/or separated from aircraft mounts during a landing accident or incident.

(1) The damage or circumstances which can result in an "Impacted" engine include impact with the ground, a collision with a service vehicle, etc. An engine dragged on the ground or against another object is considered as an impacted engine. "Dropped" engines refer to engines which are dropped entirely or on either end. Inspection requirements for impacted and dropped engines are similar and progressive in scope, that is, proceeding with further teardown is dependent on the degree of damage found at each level of inspection.
(a) For engine mounted on aircraft where pylon or nacelle damage has occurred, inspect engine mount flanges, cases, external components and plumbing, and gearbox housing and mounts. If the impact was such that debris may have entered the engine inlet, inspect engine for ingestion, and check bleed system filters and valves for debris.
1 If no damage is noted, no further action is necessary.
2 If damage is noted to external components and plumbing, replace damaged items.
3 If damage is noted to mount flanges, gearbox or gearbox mounts or cases, remove the engine and examine the front and rear N1 rotor mainshaft bearings for damage or brinelling. Borescope the engine and check the rotors for freedom of movement and listen for unusual rubbing sounds.
4 If damage is noted on N1 mainshaft bearings, remove and examine all mainshaft bearings.
5 Monitor chip detectors and oil filter on a more frequent basis during the initial return of the engine to service.
(b) For dropped engines, do as follows:
1 Remove the front and rear N1 rotor mainshaft bearings and examine for damage or brinelling. If bearing damage is noted, remove and examine all mainshaft bearings.
2 Do a visual and borescope inspection. Check for freedom of N1 and N2 rotor movement and listen for unusual rubbing sounds.
3 Monitor chip detectors and oil filter on a more frequent basis during initial return of the engine to service.

Subtask 70-50-00-910-055-A ** ON A/C NOT FOR ALL

F. Tailpipe Fires
(1) In general, tailpipe fires of short duration and extinguished by "motoring" probably have little harmful effect on the exhaust area engine parts.
(a) Examine the exhaust area for signs of scorching. Any parts that show scorching (this includes the fan duct acoustic liners, if so equipped) should be replaced.
(2) Engines which experience a more persistent tailpipe fire, or when starting overtemperature limits are exceeded during a tailpipe fire, present a greater potential for thermal stress.
(a) Remove the engine and disassemble sufficiently to determine if hot section engine parts have experienced excessive temperature or if the turbine disks have been exposed to fire. The same part disposition applies as discussed in the subsequent paragraph Accident Engine, General Inspection Guidelines.

Subtask 70-50-00-910-056-A ** ON A/C NOT FOR ALL

G. Accident Engine, General Inspection Guidelines

NOTE: Inspection is to be used in conjunction with existing TCCA approved data for engine parts (that is, data in publications such as Engine Manuals, Standard Practices Manuals and Component Maintenance Manuals).

(1) For the disassembly, cleaning, visual inspection and general inspection of the engine gaspath, remove the engine and use the shop Engine Manuals, Standard Practices Manuals, Component Maintenance Manuals.

[Rev.10 from 2021] 2026.04.01 02:20:43 UTC