A G159 first officer reported noticing a master caution warning 'right gearbox press' during cruise ...

Narrative:

On the day in question; I served as the second-in-command aboard a gulfstream 159. We were established in flight on an overwater charter flight established in the block FL210-250; holding FL220 approximately 2 hours into our route. While in the course of my duties; I observed the master warning light come on on the eyebrow dash. My right side master caution panel indicated 'right gearbox press'; meaning right gearbox pressure. The light was intermittent and remained intermittent throughout the remainder of the flight. Within a second or two; I notified the PIC of my observation and we began pulling the emergency checklists. I called out the appropriate emergency checklist; which said in one line 'gearbox low oil pressure: during cruise: accomplish manual feather checklist.' the PIC placed a satellite phone call to our home base. The PIC was unable to reach anyone for several minutes. We were located approximately 480 nautical miles from destination at this point; and I was afraid to override the PIC's determination not to immediately shut down the engine in flight. The PIC did eventually reach someone at our home base. I was not privy to that conversation because the satphone only plays into one headset - so I can only hear the PIC's conversation. I later learned that the PIC was instructed to shut down the engine. After finishing the phone conversation; the PIC informed me that he was 'not going to shut down a perfectly good engine in flight' and I presumed he was aware of facts that I was not privy to from his discussion with our maintenance and management. I radioed center and requested and was granted clearance back. I answered all questions to the controller truthfully. We were able to reach departure airport without further incident. I am going to engage my company regarding emergency procedure training and I am going to thoroughly review all systems on the aircraft to assure that we are fully complying with the manufacturer's recommended practices.

Original NASA ASRS Text

Title: A G159 First Officer reported noticing a Master Caution warning 'R GEARBOX PRESS' during cruise flight on an overwater leg. Although the checklist called for feathering the engine; the Captain decided to keep the engine running.

Narrative: On the day in question; I served as the Second-in-Command aboard a Gulfstream 159. We were established in flight on an overwater charter flight established in the block FL210-250; holding FL220 approximately 2 hours into our route. While in the course of my duties; I observed the Master Warning light come on on the eyebrow dash. My right side Master Caution Panel indicated 'R GEARBOX PRESS'; meaning right gearbox pressure. The light was intermittent and remained intermittent throughout the remainder of the flight. Within a second or two; I notified the PIC of my observation and we began pulling the emergency checklists. I called out the appropriate emergency checklist; which said in one line 'Gearbox Low Oil Pressure: DURING CRUISE: Accomplish Manual Feather Checklist.' The PIC placed a satellite phone call to our home base. The PIC was unable to reach anyone for several minutes. We were located approximately 480 nautical miles from destination at this point; and I was afraid to override the PIC's determination not to immediately shut down the engine in flight. The PIC did eventually reach someone at our home base. I was not privy to that conversation because the Satphone only plays into one headset - so I can only hear the PIC's conversation. I later learned that the PIC was instructed to shut down the engine. After finishing the phone conversation; the PIC informed me that he was 'not going to shut down a perfectly good engine in flight' and I presumed he was aware of facts that I was not privy to from his discussion with our maintenance and management. I radioed Center and requested and was granted clearance back. I answered all questions to the controller truthfully. We were able to reach departure airport without further incident. I am going to engage my company regarding emergency procedure training and I am going to thoroughly review all systems on the aircraft to assure that we are fully complying with the manufacturer's recommended practices.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	853762
Time
Date	200909
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Gulfstream II (G1159)
Operating Under FAR Part	Part 135
Flight Phase	Cruise
Route In Use	Oceanic
Flight Plan	IFR
Component
Aircraft Component	Accessory Drive Section
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Commercial Flight Crew Multiengine Flight Crew Instrument Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 80 Flight Crew Total 980 Flight Crew Type 190
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy

A G159 first officer reported noticing a master caution warning 'right gearbox press' during cruise flight on an overwater leg. Although the checklist called for feathering the engine; the captain decided to keep the engine running.