The Royal Air Force’s Boeing E-3D Sentry airborne early warning aircraft have been temporarily removed from service, as a result of “major” issues with the platform’s electrical and fire safety equipment.

The Sentry fleet recently entered routine servicing, during which the type was categorised as “unserviceable”. This led to fleet-wide operations being put on hold.

“As a result of routine technical inspections on RAF E-3D Sentry aircraft, an issue has been identified relating to the integrity of some electrical wiring and cabin conditioning systems,” the RAF tells FlightGlobal. “Safety remains our paramount concern. Therefore, the UK Sentry fleet will only fly again once the ongoing rectification work is complete.”

While the air force could not go into further detail, sources claim that on inspection, it was found that wiring under the floor was arcing and old – and in turn a fire risk – while fire blankets were found to not be fireproof.

The problems were identified a couple of weeks ago and had not previously been an issue, and an industry/air force team is now working to fix the faults and bring the aircraft back into service.

No exact timeline for the E-3D’s return to service have been revealed, but the problems are expected to be fixed in the “coming weeks”, an RAF source says.

RAF E-3D Sentry AWACS - Gary Dawson/REX Shuttersto

Gary Dawson/REX/Shutterstock

Sentry is supporting the RAF’s operations in Iraq and Syria against Islamic State insurgents. Six examples are in service with the UK, Flight Fleets Analyzer shows, ranging between 25 and 27 years in age.

Northrop Grumman provides the E-3D’s APY-2 radar, and also heads a team that provides ongoing whole-life support of the fleet.

The company was awarded an extension to the contract earlier this year, helping to keep the aircraft in service until a current planned retirement date of 2035. Northrop was unavailable for comment about the reported faults.

A mission system mid-life upgrade will also be required to keep the fleet flying until 2035. It is expected to be put out to tender in mid-2017.