Service difficulty report · Potentiometer · Swrngn SA226TC

Difficulty date
August 16, 2009
Submitted
October 23, 2009
Operation
General aviation
Make and model
Swrngn SA226TC
Aircraft time
29,691 hours
Engine
Garrtt TPE33110UA
Propeller
Hartzl HCE4N3
Part
Potentiometer
Part number
78SF2B502
Condition
Failed
Location
Nlg Steering
Part time
1,985 hours
Stage of operation
TO
How discovered
O
Nature of condition
P
Precautionary procedure
C

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

What was found

AFTER APPLYING PWR ON THE TAKEOFF ROLL ON RWY 31, ACFT BECAME DIFFICULT TO CONTROL ON THE TAKEOFF ROLL. NOSE STEERING WAS BEHAVING AS IF IT WAS STILL IN FULL `PARK` MODE, WITHOUT THE PARK BUTTON BEING DEPRESSED, AND STEERING WAS VERY SENSITIVE AND ALMOST IMPOSSIBLE TO KEEP STRAIGHT. AROUND 60 KNOTS, DECISION WAS MADE TO ABORT THE TAKEOFF. EXIT WAS MADE ONTO TAXIWAY VICTOR, AND FLIGHT WAS RETURNED TO THE APRON. NOSE STEER FAIL LIGHT FAILED TO COME ON DURING THE EVENT. DURING THE TAXI BACK, THE ACFT WAS STILL DIFFICULT TO CONTROL. MX TROUBLESHOT AND FOUND THE NOSE WHEEL STEERING FOLLOWUP POTENTIOMETER LOCATED ON NOSE GEAR, HAD FAILED. THE SHAFT WHICH IS SECURED TO THE 27-82529-041 NWS BRACKET WAS FOUND BROKEN OFF AND SEPARATED FROM THE POTENTIOMETER HSG. MX REPLACED THE BROKEN POTENTIOMETER, TESTED THE SYS AND RETURNED ACFT TO SERVICE WITH NO FURTHER FAULTS. THE NWS STEERING SYS DID NOT PROVIDE AN ANNUNCIATOR WARNING TO THE CREW OF THE FAILURE OR THE DISCREPANCY BETWEEN THE COMMAND POTENTIOMETERS ON THE RUDDER PEDALS AND THE FOLLOWUP POTENTIOMETER ON THE NOSE GEAR. IF THIS WERE TO HAVE OCCURED DURING THE LANDING PHASE OF FLIGHT, THIS FAULT MAY HAVE RESULTED IN THE ACFT DEPARTING THE RUNWAY.