What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
Narrative: the aircraft made a normal approach and landing with all airspeed call out on time. After touch down the aircraft veered right, pilot applied heavy left braking and left rudder. The aircraft continued veering right, left reverser was deployed, right turn continued and directional control could not be maintained. Full thrust reversers were deployed on both engines, the airplane exited the runway striking a marker sign and runway light, coming to a stop 224 feet from the runway between runway 10R and the taxiway. There were 1900 feet of skid marks, starting with the right main, as heavy braking was applied skid marks appear on the left main gear and the nose wheel. Repairs to the aircraft were made in Boise, ID, a ferry permit issued from boi FSDO, and the airplane ferried to signature flight support in minneapolis, a factory authorized service center. Approximately 144 items were checked and the following had relation to lateral control. Nose wheel steering cable tension was adjusted. An intermittent left thrust reverser deploy switch was replaced. Left thrust reverser hydraulic valve connector, strain relief connector added, cold solder joint repaired on left thrust reverser control valve. The scenario that fits the evidence in this incident is a condition in which the captain is commanding full reverse on the left thrust reverser but it is developing forward thrust. This condition could exist if power was interrupted to the reverser control valve causing the system to fail-safe to the slow position. The safety feed-back system is very subtle and difficult to feel in a low power setting. It is also fact that this system only triggers once, moving the fuel control to the idle and thereby, moving the thrust lever. If this movement occurs in a low power regime, it will not have enough force to latch the reverse lever to slow, in this instance there is nothing to prevent the pilot from pulling the reverse thrust lever again, giving forward thrust if the reverse buckets are not deployed. Power may be interrupted to a control valve stowing the reverser buckets either by failure of a component, a tripped circuit breaker, or by inadvertent deactivation of the arming switch. The following will be standard operating procedures and check lists effective immediately for the westwind, N163WC. Lift dump deployment is no longer automatic upon touch down, the captain will command deployment of lift dumps by the co-pilot. Deployment of thrust reversers, and braking will commence sequentially rather than simultaneously. A change to the thrust reverser check on the taxi check list has been made.
As the FAA filed it
NARRATIVE: THE AIRCRAFT MADE A NORMAL APPROACH AND LANDING WITH ALL AIRSPEED CALL OUT ON TIME. AFTER TOUCH DOWN THE AIRCRAFT VEERED RIGHT, PILOT APPLIED HEAVY LEFT BRAKING AND LEFT RUDDER. THE AIRCRAFT CONTINUED VEERING RIGHT, LEFT REVERSER WAS DEPLOYED, RIGHT TURN CONTINUED AND DIRECTIONAL CONTROL COULD NOT BE MAINTAINED. FULL THRUST REVERSERS WERE DEPLOYED ON BOTH ENGINES, THE AIRPLANE EXITED THE RUNWAY STRIKING A MARKER SIGN AND RUNWAY LIGHT, COMING TO A STOP 224 FEET FROM THE RUNWAY BETWEEN RUNWAY 10R AND THE TAXIWAY. THERE WERE 1900 FEET OF SKID MARKS, STARTING WITH THE RIGHT MAIN, AS HEAVY BRAKING WAS APPLIED SKID MARKS APPEAR ON THE LEFT MAIN GEAR AND THE NOSE WHEEL. REPAIRS TO THE AIRCRAFT WERE MADE IN BOISE, ID, A FERRY PERMIT ISSUED FROM BOI FSDO, AND THE AIRPLANE FERRIED TO SIGNATURE FLIGHT SUPPORT IN MINNEAPOLIS, A FACTORY AUTHORIZED SERVICE CENTER. APPROXIMATELY 144 ITEMS WERE CHECKED AND THE FOLLOWING HAD RELATION TO LATERAL CONTROL. NOSE WHEEL STEERING CABLE TENSION WAS ADJUSTED. AN INTERMITTENT LEFT THRUST REVERSER DEPLOY SWITCH WAS REPLACED. LEFT THRUST REVERSER HYDRAULIC VALVE CONNECTOR, STRAIN RELIEF CONNECTOR ADDED, COLD SOLDER JOINT REPAIRED ON LEFT THRUST REVERSER CONTROL VALVE. THE SCENARIO THAT FITS THE EVIDENCE IN THIS INCIDENT IS A CONDITION IN WHICH THE CAPTAIN IS COMMANDING FULL REVERSE ON THE LEFT THRUST REVERSER BUT IT IS DEVELOPING FORWARD THRUST. THIS CONDITION COULD EXIST IF POWER WAS INTERRUPTED TO THE REVERSER CONTROL VALVE CAUSING THE SYSTEM TO FAIL-SAFE TO THE SLOW POSITION. THE SAFETY FEED-BACK SYSTEM IS VERY SUBTLE AND DIFFICULT TO FEEL IN A LOW POWER SETTING. IT IS ALSO FACT THAT THIS SYSTEM ONLY TRIGGERS ONCE, MOVING THE FUEL CONTROL TO THE IDLE AND THEREBY, MOVING THE THRUST LEVER. IF THIS MOVEMENT OCCURS IN A LOW POWER REGIME, IT WILL NOT HAVE ENOUGH FORCE TO LATCH THE REVERSE LEVER TO SLOW, IN THIS INSTANCE THERE IS NOTHING TO PREVENT THE PILOT FROM PULLING THE REVERSE THRUST LEVER AGAIN, GIVING FORWARD THRUST IF THE REVERSE BUCKETS ARE NOT DEPLOYED. POWER MAY BE INTERRUPTED TO A CONTROL VALVE STOWING THE REVERSER BUCKETS EITHER BY FAILURE OF A COMPONENT, A TRIPPED CIRCUIT BREAKER, OR BY INADVERTENT DEACTIVATION OF THE ARMING SWITCH. THE FOLLOWING WILL BE STANDARD OPERATING PROCEDURES AND CHECK LISTS EFFECTIVE IMMEDIATELY FOR THE WESTWIND, N163WC. LIFT DUMP DEPLOYMENT IS NO LONGER AUTOMATIC UPON TOUCH DOWN, THE CAPTAIN WILL COMMAND DEPLOYMENT OF LIFT DUMPS BY THE CO-PILOT. DEPLOYMENT OF THRUST REVERSERS, AND BRAKING WILL COMMENCE SEQUENTIALLY RATHER THAN SIMULTANEOUSLY. A CHANGE TO THE THRUST REVERSER CHECK ON THE TAXI CHECK LIST HAS BEEN MADE.