S92 captain experiences a mgb chip light at 5;000 feet over the gulf of mexico and elects to return ...

Narrative:

During an IFR helicopter flight over the gulf of mexico at 5;000 feet; the mgb [main gear box] chip caution light illuminated. The emergency procedure was performed and there were no associated secondary indications. The emergency checklist called for a landing as soon as practical. History of the S92 has included a main transmission failure resulting in fatalities and our company trains us to treat any mbg issue very seriously. We elected to turn around and return to a shore based heliport or airport for landing. I had slowed the aircraft to 100 knots airspeed during the ep and the second in command began attempting to advise the center controller. The frequency is weak in this coverage area and was congested. After the third call to the controller and being told to 'just standby'; I chose to begin my turn to the airport. Subsequently; he saw the turn and questioned our action. The sic stated: we had a mgb chip and need to return and descend to a lower altitude. He began chastising us for deviating from our clearance. I came up on the radio and explained that we had tried to contact him several times and in the event of an emergency I was authorized to deviate as required. He then gave us an immediate descent to 4;000 feet and an immediate climb to 6;000 feet to the aircraft behind us. Prior to being handed off to approach; I was instructed to call a phone number after landing for 'possible violation action.' we landed at and during approach the input 2 chip caution light illuminated also. Both chip plugs had excessive metal particles and the aircraft was grounded. Reflecting back on the situation; I should have immediately announced 'emergency' over the center frequency to get the controller's attention and gain priority over the other traffic thereby getting expedited handling.

Original NASA ASRS Text

Title: S92 Captain experiences a MGB chip light at 5;000 feet over the Gulf of Mexico and elects to return to the departure airport. ATC cannot be contacted immediately due to frequency congestion and a turn back is initiated prior to receiving clearance. A second chip light illuminates prior to landing.

Narrative: During an IFR helicopter flight over the Gulf of Mexico at 5;000 feet; the MGB [Main Gear Box] Chip caution light illuminated. The emergency procedure was performed and there were no associated secondary indications. The Emergency Checklist called for a landing as soon as practical. History of the S92 has included a Main Transmission failure resulting in fatalities and our company trains us to treat any MBG issue very seriously. We elected to turn around and return to a shore based heliport or airport for landing. I had slowed the aircraft to 100 knots airspeed during the EP and the second in command began attempting to advise the Center Controller. The frequency is weak in this coverage area and was congested. After the third call to the Controller and being told to 'Just Standby'; I chose to begin my turn to the airport. Subsequently; he saw the turn and questioned our action. The SIC stated: we had a MGB Chip and need to return and descend to a lower altitude. He began chastising us for deviating from our clearance. I came up on the radio and explained that we had tried to contact him several times and in the event of an emergency I was authorized to deviate as required. He then gave us an immediate descent to 4;000 feet and an immediate climb to 6;000 feet to the aircraft behind us. Prior to being handed off to Approach; I was instructed to call a phone number after landing for 'Possible Violation action.' We landed at and during approach the Input 2 Chip caution light illuminated also. Both chip plugs had excessive metal particles and the aircraft was grounded. Reflecting back on the situation; I should have immediately announced 'Emergency' over the Center frequency to get the Controller's attention and gain priority over the other traffic thereby getting expedited handling.

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.

Attributes
ACN	1180765
Time
Date	201406
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	Sikorsky Helicopter Undifferentiated or Other Model
Operating Under FAR Part	Part 135
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	Helicopter Gearbox and Drive
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 11000 Flight Crew Type 600
Events
Anomaly	ATC Issue All Types Aircraft Equipment Problem Critical Deviation - Track / Heading All Types

S92 captain experiences a mgb chip light at 5;000 feet over the gulf of mexico and elects to return to the departure airport. ATC cannot be contacted immediately due to frequency congestion and a turn back is initiated prior to receiving clearance. A second chip light illuminates prior to landing.