Garmin GSU 75 Series Installation Manual page 56

The following are potential causes for failure of the engine run-up test:
a) Excessive flexibility of GSU 75 and/or GMU 44 mechanical mounting with respect to air-
frame (See
b) Vibrational motion of GSU 75 and/or GMU 44 caused by neighboring equipment and/or
supports.
c) Mounting of GSU 75 at a location that is subject to severe vibrations (example; close to an
engine mount.)
d) Mounting screws and other hardware for GSU 75 and/or GMU 44 not firmly attached.
e) Absence of mounting supports recommended by the aircraft manufacturer.
f) GSU 75 connector not firmly attached to unit.
g) Cabling leading to GSU 75 or GMU 44 not firmly secured to supporting structure.
h) An engine/propeller combination that is significantly out of balance.
In some aircraft, attempting the engine runup test on a day with very strong and/or gusty winds may cause
the test to occasionally fail. However, windy conditions should not be taken as evidence that the test
would pass in calm conditions; an actual pass is required before the installation can be considered
adequate.
5. Press the ENTER key on the PFD to conclude this procedure.
190-01639-00
Rev. 6
The document reference is online, please check the correspondence between the online documentation and the printed version.
Section 2.11).
GSU 75 ADAHRS Installation Manual
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