TB 1--1520--251--20--03
1. Current position -- load into KU.
2. INU 1 and INU 2 -- reset. Check TSD page for the HDG selection displayed.
3. PSN -- Select.
4. POS -- Select.
5. KU enter button -- press.
6. UPT -- Select.
7. Time -- select. Enter current Zulu time.
8. Date -- select. Enter current Zulu date.
(3) Change to TM 1--1520--251--10, page 9--18.2, para 9--23.5, add the following --
CAUTION
In flight, depending on airspeed, an uncommanded scheduling down of the
stabilator can generate significant aircraft pitch changes and decelerative
forces. The instinctive AFT cyclic input applied will begin to slow the aircraft.
However, a reduction in collective generates an additional pitch down
moment which aggravates this situation and should be avoided.
9.23.5 EGI In--Flight Misalignment. Misalignment of an EGI will be indicated by a position confidence error
of 1.85K and erratically climbing and/or descending or EGI present position information on the TSD page is
more than 1 nautical mile in error and growing. In the event of an EGI misalignment perform the following --
(a) Position update -- Perform. Monitor position confidence.
If misalignment continues --
(b) Airspeed -- Adjust to 80 KTAS or less.
(c) Stabilator -- Manually control as required.
(d) Land as soon as practicable.
(4) Urgent change to TM 1--1520--251--CL, page E--17/(E--18 blank), add --
EGI In--flight Misalignment
(a) Position update -- Perform. Monitor position confidence.
If misalignment continues --
(b) Airspeed -- Adjust to 80 KTAS or less.
(c) Stabilator -- Manually control as required.
(d) Land as soon as practicable.
f. In the event the EGIs cannot be properly aligned, the aircraft status symbol will be changed to a
red //X//. The AH--64D ISAQ temporarily restricts the aircraft from performing in flight realignments of the
EGIs. The intent of the paragraph in the ISAQ that states "If a proper alignment cannot be performed on
a single EGI prior to flight, the crew will disable the nonaligned EGI by pulling the appropriate EGI 1A and
EGI 1B or EGI 2A and EGI 2B circuit breakers prior to flight" is to allow for aircraft recovery only. The
following caution is extracted from the AH--64D ISAQ. This caution is temporary and is reprinted in this
TB for emphasis to the aviators.
CAUTION
In flight, reset and realignment of the EGIs is not allowed. A successful reset
of an EGI may result in large position, attitude, and velocity errors. This in
turn may result in inappropriate scheduling of the stabilator when the FMC
reacts to the erroneous information.
10. Supply/Parts and Disposition. N/A
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