TM 1-2840-252-23-3
FAULT CODE
FAULT
A1
Q
A6
28V EM
A7
28V EM
B2
N1B
B3
N2B
B5
C/P LVDT
B6
ECL
B7
PLA
BC
RESOLVER REFERENCE
DO
OVERSPEED DRIVE
D3
OR DIODES
D6
+12V REVERSIONARY
DA
+5V REVERSIONARY
DB
REVERSIONARY SYSTEM
DD
OVERSPEED CHECK
E5
N2A/N2B DIFFERENCE
F3
N1A/N1B DIFFERENCE
c.
If any of the above faults occur, the engine must be shut down and power to the DECU cycled to clear the
faults. After power is cycled. the appropriate action must be taken to confirm the fault (run engine with ECL at
GROUND, run engine with ECL at FLIGHT, etc.) If the faults clear (hex display of "88" with ECL in ground),
the faults are to be considered due to power interrupts, and not indicative of a FADEC system fault. If the
faults do not clear, then the appropriate fault isolation action should be taken.
G-9 OPERATIONAL PROBLEMS WITHOUT CODES
There are some operational problems that may be noted that do not result in fault codes on the diagnostic display, such
as, engine torques not matched, no response to cockpit switch, etc. Refer to fault isolation procedure figures 142 through
157 for these problems.
G-10 USING THE FAULT ISOLATION DIAGRAMS
a. Display current fault codes using the procedure defined in paragraph G-7. Record all fault codes. If a system
fault has been observed that does not result in a fault code, record the symptom(s).
NOTE
Under specific conditions, it is possible for an undefined fault code not listed in Table 1 to appear on the
hex display. In this event, the procedure given in figure 158 shall be followed.
b. If only one fault is noted, locate the fault by fault code or description in Table 1. Go to the figure listed for that
fault and follow the procedure.
G-8
