Volume 4 AIRCRAFT EQUIPMENT AND OPERATIONAL AUTHORIZATIONS
chapter 14 GENERAL OPERATING AND FLIGHT RULES—MAINTENANCE ISSUES
Section 12 Powerplant Repairs
4-1621 BACKGROUND. This section provides classifications of turbine
engine structural parts and the general classifications of engine repairs.
4-1622 TURBINE ENGINE PART CLASSIFICATIONS. Although each manufacturer
may not use the identical terminology used below, what they use will be equivalent
to the following:
A. Structural Engine Parts. To include the following:
· All frames,
· All casings/housings,
· Engine mounts and associated engine structures, and
· Complete rotor assemblies.
B. Engine Frames. To include the following:
· Front frames or front-bearing support,
· Compressor rear frame,
· Turbine mid-frame, and
· Turbine rear-frame or rear-bearing support.
C. Engine Combustion Casings/Housings. To include the following:
· Fan casing,
· Compressor (low and high),
· Combustor casing/housing,
· Turbine casing/housing, and
· Accessory gear-case housing.
4-1623 ENGINE REPAIR CLASSIFICATIONS. The following will apply to turbine engines and reciprocating engines, as applicable:
A. Turbine Engines. The following repair classifications will apply:
1) The changing of modules is not considered a major repair.
2) The disassembly of any of the main sections of a turbine engine
should be considered a major repair. The main sections consist of the following:
· Fan section,
· Compressor section (low and high pressure),
· Combustion section,
· Turbine section, and
· Accessory section.
B. Reciprocating Engines. Major and minor repairs to structural
parts of reciprocating engines are classified as follows:
1) Major repairs include the following:
· Welding of crankcases,
· Machining operations necessitated by a weld repair,
· Crankshaft grinding,
· Camshaft recontouring and similar complex precision machining,
· Boring of crankshaft and camshaft bosses, and
· Machining of oil pump housings and accessory drive pads following weld repairs.
2) Minor repairs include simple machine operations, such as spot
facing, lapping and grinding valves, and reaming valve guides in accordance
with the manufacturer’s overhaul and service instructions.
C. Further Guidance. Further guidance on major and minor repairs,
approved data, and approval for return to service can be found in
Volume 4, Chapter 9, Section 1, Perform Field Approval of Major Repairs and Major Alterations.
RESERVED. Paragraphs 4-1624 through 4-1630.