Service difficulty report · Computer · Bolkms BK117A4

Difficulty date
November 1, 2008
Submitted
November 3, 2008
Operation
Air carrier
Aircraft
N68AM
Make and model
Bolkms BK117A4
Aircraft serial
7111
Part
Computer
Part number
117884141
Condition
Intermittent
Location
Autopilot Sys
Stage of operation
CL
How discovered
O
Nature of condition
F
Precautionary procedure
A

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

What was found

PILOT REPORT - DURING A FLIGHT TO SAINT FRANCIS HOSPITAL, THE AIRCRAFT BEGAN TO HAVE VERY STRONG UNCOMMANDED YAW INPUTS. THE PILOT DISENGAGED THE YAW CSAS BUT STILL FELT WHAT HE THOUGHT WAS UNCOMMANDED YAW INPUTS. BOTH ENGINES INDICATED NORMAL. THE PILOT THEN MADE A PRECAUTIONARY LANDING AND NOTIFIED MAINTENANCE. MAINTENANCE REPORT - WHEN THE MECHANIC MADE A VISUAL INSPECTION OF THE TAIL ROTOR AND CONTROLS. THE MECHANIC ALSO CLEANED AND REINSTALLED THE YAW CSAS COMPUTER ELECTRICAL CONNECTORS. THE AIRCRAFT WAS THEN FLOWN IN THE LOCAL AREA AND HAD NO PROBLEMS. THE AIRCRAFT WAS RETURNED TO SERVICE AND FLOWN BACK TO THE BASE. APPROXIMATELY TWO HOUR LATER, THE NEXT DUTY PILOT EXPERIENCED THE SAME UNCOMMANDED YAW INPUTS. THE AIRCRAFT WAS GROUNDED AND THE MECHANIC ORDERED A YAW CSAS COMPUTER. THE COMPUTER WAS CHANGED THE NEXT DAY AND THE AIRCRAFT WAS FLOWN AGAIN FOR 15 MINUTES WITH NO YAW ISSUES. THE AIRCRAFT WAS THEN PUT BACK INTO SERVICE AND HAS HAD NO FURTHER ISSUES.