Giv-sp first officer reported pitch trim became inoperative in cruise; flight crew decided to divert...

Attributes
ACN	1317304
Time
Date	201512
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Gulfstream IV / G350 / G450
Operating Under FAR Part	Part 135
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Horizontal Stabilizer Trim
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Inflight Event / Encounter Weather / Turbulence

Narrative:

Noticed an 'el mstrm nse up/dn' amber cas lite. Soon the autopilot kicked off. Reset pitch trim and FGC1 and 2 lites on. The elec and manual trim were frozen. We followed QRH but still no control. We elected to descend to a warmer alt and divert. At around 15000 ft the trim was regained. We flew normal landing. We had no autopilot after pitch trim was disconnected until we regained pitch trim.there probably was a malfunction of the trim motor heater which we would have no indication of in the cockpit. Since we had no idea what was causing the malfunction we diverted to a suitable alternate to avoid rvsm airspace. Alt control was at times + or - 100 feet.

Original NASA ASRS Text

Title: GIV-SP First Officer reported pitch trim became inoperative in cruise; flight crew decided to divert and regained pitch trim after descending to a warmer altitude.

Narrative: Noticed an 'el mstrm nse up/dn' amber CAS lite. Soon the autopilot kicked off. Reset pitch trim and FGC1 and 2 lites on. The elec and manual trim were frozen. We followed QRH but still no control. We elected to descend to a warmer alt and divert. At around 15000 ft the trim was regained. We flew normal landing. We had no autopilot after pitch trim was disconnected until we regained pitch trim.There probably was a malfunction of the trim motor heater which we would have no indication of in the cockpit. Since we had no idea what was causing the malfunction we diverted to a suitable alternate to avoid RVSM airspace. Alt control was at times + or - 100 feet.

Data retrieved from NASA's ASRS site 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.

Giv-sp first officer reported pitch trim became inoperative in cruise; flight crew decided to divert and regained pitch trim after descending to a warmer altitude.