SDR 98ZZZX476

Service difficulty report · Flight Director · Swrngn SA226AT

Difficulty date
January 28, 1998
Submitted
March 26, 2000
Operation
General aviation
Aircraft
N59TP
Make and model
Swrngn SA226AT
Aircraft serial
T26161
Part
Flight Director
Part number
329B7A
Condition
Failed
Location
Pitch Synchro
Component
Collins
Stage of operation
IN
Nature of condition
O
Precautionary procedure
K

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

WHEN RECEIVED, THE FLIGHT DIRECTOR PRESENTATION WAS SHOWING AN ATTITUDE OF 70 DEGREES UP WHEN ENERGIZED. IT SHOULD HAVE BEEN SHOWING ZERO ATTITUDE. THE PROBLEM WAS TRACED TO THE PITCH SYNCHRO. THIS SYNCHRO HAD LOCKED UP DUE TO THE LAMINATION IMPREGNATING MATERIAL GETTING INTO THE VERY SMALL AIR GAP BETWEEN THE ROTOR AND STATOR OF THE SYNCHRO. ONLY ONE SET SCREW WAS USED TO HOLD THE SYNCHRO DRIVE GEAR ON THE SYNCHRO SHAFT; WHEN SYNCHRO LOCKED UP, THE GEAR SLIPPED ON THE SHAFT ALLOWING SYNCHRO TO GIVE THE WRONG INFO TO THE PRESENTATION. AFTER ELIMINATING CONTAMINATION PROBLEM IN THE SYNCRHO, A FLAT WAS MACHINED ON THE SYNCHRO SHAFT. TWO SET SCREWS WERE USED TO SECURE THE SYNCHRO DRIVE GEAR.