Eurocopter issues safety alert over EC135 fuel gauge error

* Bond had grounded its EC135 fleet on fuel gauge fault

* Possible similar errors found in other aircraft -Eurocopter

* Alert comes after EC135 crashed in Glasgow

* Eurocopter: Too early to draw connection of defect to crash

By Belinda Goldsmith

LONDON, Dec 16 (Reuters) - Eurocopter issued a safety alert to operators of its EC135 helicopters on Monday after aircraft from the same fleet as one that crashed into a Scottish pub last month killing 10 people and some in Europe were found with a fuel gauge defect.

UK-based air services company Bond Aviation grounded its fleet of 38 EC135s on Dec. 11, after an air ambulance, one of its 22 aircraft leased in Britain, was found to have a fuel indicator problem. Tests found others also had the same fault.

A spokesman for Eurocopter, a unit of European aerospace and defence company EADS (TLO: EAD-U.TI - news) , said tests by Bond and two other EC135 operators in Europe found possible similar supply-tank fuel gauging errors that overestimated the fuel on board.

The discovery of the fault came 12 days after one of Bond's EC135s leased to the police crashed into the Clutha pub in Glasgow killing three crew and 7 others.

The helicopter was only minutes away from returning to its base when it dropped vertically on to the roof of the pub.

"It is too early to say whether there is any connection between the fuel gauge defect and the accident in Glasgow," a spokeswoman for Eurocopter said on Tuesday.

EADS said that initial analysis showed that the fuel gauge defect could lead to pilots to overestimate how much fuel was left in the supply tanks.

"All crews should be aware that in the worst case a red warning "Low Fuel" could appear without any amber FUEL Caution before," it said in a statement.

The spokeswoman added that an EC135 pilot would have eight to 10 minutes' time to land the aircraft once the "Low Fuel" warning appeared.

Eurocopter said it was issuing a safety notice to remind all EC135 operators to follow the safety procedures already in place and outlined in the flight manual, regardless of the aircraft's fuel quantity indication.

The company said it would "update its Safety Information Notice as needed" with investigations continuing.

A preliminary report from the Air Accidents Investigation Branch (AAIB) stated last week that initial checks in connection with the Glasgow crash found no engine or gearbox problems and fuel on board. Investigations are continuing..

Bond Aviation said in a statement on Monday that the results of the tests on the rest of its helicopters were validated by Eurocopter, and appropriate repairs were made before returning the aircraft to service.

No one at Bond was immediately available to comment on how many of its aircraft were found to have the fault.

"We also took the decision to increase safety barriers by mandating that all our EC135s should maintain a minimum of 90kg of fuel onboard at all times," Bond Aviation added.

Following the Glasgow crash and the grounding of Bond Aviation's fleet, transport union RMT has called for a full public inquiry into helicopter safety, concerned there has been three incidents involving helicopters in the UK in four months.

In August, four oil rig contractors were killed when a Super Puma L2 made by Eurocopter crashed into the sea off Shetland's southern coast, causing a temporary halt on all Puma (Berlin: PUM.BE - news) flights. An investigation found no technical fault.