TASK 2 - FLAT TRACK MAIN ROTOR ON THE GROUND
The preferred method of tracking the OH-58D is tracking it with the MMS installed. Removing the sight and
working the rotor until smooth and then reinstalling the sight is considered an obsolete method and could result in
high vibration levels at Idle RPM when the sight is reinstalled. Working the rotor with the sight installed and using
the OH-58DM script file will preclude having high vibration levels at idle RPM.
When using the GNDTRK flight plan in the OH-58D setup file, the correct procedure is to obtain a track picture of
less than 0.2 inches at both 65%-NR and 35%-TQ test conditions. The diagnostics will use the main rotor pitch
change links to obtain a track not greater than 0.2 inches at 65%-NR and then use the trim tabs to correct for less
than 0.2 inches track change from 65%-NR to 35%-TQ.
When using the GNDTRK flight plan in the OH-58DM setup file, the correct procedure is to obtain a track picture
of <0.2 inches at 65% nr using pitch change links.
PROCEDURE 1: PREPARATION
a. Install test equipment. See task 1).
b. Operate aircraft at appropriate rotor speed (see table 1 or table 2).
c. Turn on DAU.
d. Turn on CADU.
PROCEDURE 2: PERFORM GROUND TRACK (GNDTRK) MEASUREMENT
a. Press QUIT on the CADU until all selections are undefined.
b. Use cursor keys to highlight Aircraft Type. Press DO.
c. Select aircraft type OH-58D for aircraft without MMS and OH-58DM for those aircraft with MMS, then press
d. Tail Number is highlighted. Press DO.
e. Use cursor keys to highlight a tail number or enter a new tail number (up to seven digits), then press DO.
Flight Plan is highlighted. Press DO.
g. Use cursor keys to highlight GNDTRK. Press DO.
h. Enter the measure mode by pressing F1.
Press DO when the aircraft is stable at the highlighted selection. The first time the DO key is pressed, the
system performs a self-test of all installed equipment and readies the DAU to acquire data for that Test State
(the CADU will prompt the operator with an asterisk and the test condition when all equipment is ready). Verify
that the aircraft is at the required Test State (65%-NR or 35%-TQ for OH-58D aircraft with SG, 65%nr for
OH-58DM aircraft) and press DO again. Perform this operation each time a measurement is completed and
another Test State is highlighted. The AVA will acquire track and vibration data and return to the selection
After the last measurement is completed, press DO on Finish, then press DO on Diagnostics. If
measurements are within specified limits, press QUIT to Main Menu and proceed to task 3.
k. If measured values exceed specifications, press DO to execute diagnostics. AVA will make recommendations
to correct track using pitch change links and trim tabs.
Shut down aircraft and perform all corrections displayed on the diagnostic screen. Check to ensure that all
screens of a multiple screen solution have been displayed. Do not use a partial set of adjustments.
m. After corrections are installed, repeat procedure 2 until ground track criteria are met.
n. Proceed to task 3.