A jetstream 4100 in cruise at 16000 ft declared an emergency and diverted due to being unable to tri...

Attributes
ACN	418475
Time
Date	199810
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : msn
State Reference	WI
Altitude	msl bound lower : 16000 msl bound upper : 16000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other other other
Route In Use	enroute airway : zau
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : instrument pilot : cfi pilot : atp
Experience	flight time last 90 days : 180 flight time total : 3940 flight time type : 1650
ASRS Report	418475
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical non adherence : far non adherence : published procedure other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

At cruise (16000 ft) with autoplt selected on trim, warning lights illuminated. The PF (first officer) selected the autoplt off and aircraft had a lot of nose up pressure. First officer attempted to trim aircraft via electrical trim but was unable to operate (move trim). Autoplt trim master switch was selected off (PIC action) and manual trim change was attempted with no results (no trim). The trim/trim was stuck in autoelectrical/manual modes. I (PIC captain) assumed control of aircraft. Emergency was declared and flight xyz started a 180 degree turn toward msn, wi. To release some control pressure, I (captain PIC) slowed the aircraft speed. At about 170 KIAS and with some application of pressure on control trim wheel, trim became free and all other operations of flight controls became normal (no up/down pressures). Landed at msn with no further problems. ZZZ (company air carrier) flight control and ZZZ maintenance operations were notified by the crew and by msn station operations. I was instructed by ZZZ flight control and ZZZ maintenance control to open the cockpit voice recorder and flight data recorder circuit breakers upon NTSB request. Air carrier aircraft maintenance flight log discrepancy #2. ZZZ maintenance control was in contact with the NTSB and ZZZ maintenance control contracted an a&P to inspect aircraft (a&P not from air carrier company but from msn FBO). After working with the a&P (I was instructed by the a&P to situation in the flight deck and move the electric/manual trim) the problem did not duplicate on the ground. The a&P then proceeded to remove a tail section of the aircraft to better inspect the trim components. After his inspection, he reported to me (PIC) and via phone to ZZZ maintenance control (mxmx) that he had found a 'socket' (work tool) in the area of his inspection. The a&P then spoke to ZZZ maintenance control. The a&P then (instructed by ZZZ maintenance control) MEL'ed the autoplt functions. I (PIC) then spoke to ZZZ maintenance control and was told by ZZZ maintenance mxmx to bring back the 'socket' to our home base in ZZZ. I was told to give it to bzxx in airport ZZZ maintenance office/operations. I did just so.

Original NASA ASRS Text

Title: A JETSTREAM 4100 IN CRUISE AT 16000 FT DECLARED AN EMER AND DIVERTED DUE TO BEING UNABLE TO TRIM THE ACFT WITH AUTOPLT, MAIN ELECTRIC OR MANUAL SYS CAUSED BY A SOCKET TOOL OBSTRUCTING THE TRIM MECHANISM.

Narrative: AT CRUISE (16000 FT) WITH AUTOPLT SELECTED ON TRIM, WARNING LIGHTS ILLUMINATED. THE PF (FO) SELECTED THE AUTOPLT OFF AND ACFT HAD A LOT OF NOSE UP PRESSURE. FO ATTEMPTED TO TRIM ACFT VIA ELECTRICAL TRIM BUT WAS UNABLE TO OPERATE (MOVE TRIM). AUTOPLT TRIM MASTER SWITCH WAS SELECTED OFF (PIC ACTION) AND MANUAL TRIM CHANGE WAS ATTEMPTED WITH NO RESULTS (NO TRIM). THE TRIM/TRIM WAS STUCK IN AUTOELECTRICAL/MANUAL MODES. I (PIC CAPT) ASSUMED CTL OF ACFT. EMER WAS DECLARED AND FLT XYZ STARTED A 180 DEG TURN TOWARD MSN, WI. TO RELEASE SOME CTL PRESSURE, I (CAPT PIC) SLOWED THE ACFT SPD. AT ABOUT 170 KIAS AND WITH SOME APPLICATION OF PRESSURE ON CTL TRIM WHEEL, TRIM BECAME FREE AND ALL OTHER OPS OF FLT CTLS BECAME NORMAL (NO UP/DOWN PRESSURES). LANDED AT MSN WITH NO FURTHER PROBS. ZZZ (COMPANY ACR) FLT CTL AND ZZZ MAINT OPS WERE NOTIFIED BY THE CREW AND BY MSN STATION OPS. I WAS INSTRUCTED BY ZZZ FLT CTL AND ZZZ MAINT CTL TO OPEN THE COCKPIT VOICE RECORDER AND FLT DATA RECORDER CIRCUIT BREAKERS UPON NTSB REQUEST. ACR ACFT MAINT FLT LOG DISCREPANCY #2. ZZZ MAINT CTL WAS IN CONTACT WITH THE NTSB AND ZZZ MAINT CTL CONTRACTED AN A&P TO INSPECT ACFT (A&P NOT FROM ACR COMPANY BUT FROM MSN FBO). AFTER WORKING WITH THE A&P (I WAS INSTRUCTED BY THE A&P TO SIT IN THE FLT DECK AND MOVE THE ELECTRIC/MANUAL TRIM) THE PROB DID NOT DUPLICATE ON THE GND. THE A&P THEN PROCEEDED TO REMOVE A TAIL SECTION OF THE ACFT TO BETTER INSPECT THE TRIM COMPONENTS. AFTER HIS INSPECTION, HE RPTED TO ME (PIC) AND VIA PHONE TO ZZZ MAINT CTL (MXMX) THAT HE HAD FOUND A 'SOCKET' (WORK TOOL) IN THE AREA OF HIS INSPECTION. THE A&P THEN SPOKE TO ZZZ MAINT CTL. THE A&P THEN (INSTRUCTED BY ZZZ MAINT CTL) MEL'ED THE AUTOPLT FUNCTIONS. I (PIC) THEN SPOKE TO ZZZ MAINT CTL AND WAS TOLD BY ZZZ MAINT MXMX TO BRING BACK THE 'SOCKET' TO OUR HOME BASE IN ZZZ. I WAS TOLD TO GIVE IT TO BZXX IN ARPT ZZZ MAINT OFFICE/OPS. I DID JUST SO.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

A jetstream 4100 in cruise at 16000 ft declared an emergency and diverted due to being unable to trim the aircraft with autoplt, main electric or manual system caused by a socket tool obstructing the trim mechanism.