rotor is replaceable, the repair includes com-
applicable MIMs or disassembled for further
repair.
pressor rotor replacement and/or disassembly.
NOTE: The terms "first-degree repair"
and "complete engine repair" (CER) are
WARNING
synonymous. CER is used primarily with
older engines that are not included in the
Many of the chemical solutions and their
three-degree program.
components used in cleaning, inspection,
and repair are toxic, flammable, and
extremely corrosive. Improper mixing or
SECOND-DEGREE REPAIR
use of these chemical can produce violent
reactions, rapid heat generation, and
Second-degree repair is also the repair of a
explosive/toxic gases. Personnel perform-
damaged or nonoperating gas turbine engine and
ing maintenance procedures should consult
its accessories or components. The difference is
the applicable maintenance instruction
that second-degree repair will normally include
manuals and be familiar with the safety
the repair/replacement of turbine rotors and
precautions associated with the hazardous
combustion sections. Repairs include afterburners
materials or equipment. The warnings in
and the replacement of externally damaged,
these technical manuals identify the types
deteriorated, or time-limited components, gear-
of hazards and precautions to take. The
boxes, or accessories. Minor repair to the
Material Safety Data Sheets (MSDS) and
compressor section is made in second-degree
your safety office have specific informa-
repair. The repair or replacement of reduction
tion for hazardous material in your work
gearboxes and torque shafts of turboshaft engines
center.
comes under second-degree repair. The repair or
replacement of compressor fans of turbofan
engines also comes under second-degree repair
CLEANING
activities.
Good mechanics clean all engine parts
thoroughly before inspecting them. Cleaning and
THIRD-DEGREE REPAIR
close inspection make it possible to detect
faults that endanger safe engine operation and
The third-degree repair encompasses major
maximum performance. The primary purpose of
engine inspections and the same gas turbine engine
engine parts cleaning is to accomplish the
repair capability as second-degree maintenance.
following:
Certain functions that require high maintenance
man-hours and are of a low incidence rate are
1. Permit thorough inspection of components
excluded. The functions described represent broad
for flaws, damage, and dimension wear.
generalities. Refer to the appropriate engine
2. Prepare surfaces for repair (plating,
maintenance plan or intermediate maintenance
welding, or painting).
manual to determine the degree of assignment for
3. Remove organic or inorganic coatings for
specific repair functions.
inspection of underlying surfaces or remove
coatings adversely affecting engine performance.
AIRCRAFT INTERMEDIATE
Selection of cleaning materials and processes
MAINTENANCE DEPARTMENT
for any engine part is determined by the nature
of the soil, the type of metal or coatings, and the
Once an engine arrives at an AIMD activity,
degree of cleanliness necessary for a thorough
inspection and repair.
it is cleaned and evaluated for repair. If inducted
Generally, engine parts operating in relatively
for repair, a major inspection and all repairs
low temperature ranges (cold section parts) are
required to place the engine back in ready-for-
cleaned by solvent washing, decreasing tanks, and
issue (RFI) status are accomplished. The first
.
vapor decreasing. Cleaning engine parts that
steps for inspecting aircraft engines include the
operate in hot sections of the engine (combustion
cleaning and the marking of parts. After clean-
and turbine sections) require more comprehensive
ing, engines are inspected in accordance with
10-2
