EU air safety agency grounds Airbus Super Puma helicopters

* EASA temporarily grounds H225 LP and AS332 L2 helicopters

* Norway widens ban of Airbus H225 helicopter

* Ban now also includes search and rescue mission

* Ban follows discovery of metal fatigue in crashed helicopter (Adds EASA flight prohibition)

OSLO, June 2 (Reuters) - The European Aviation Safety Authority on Thursday grounded Airbus H225 LP and AS332 L2 Super Puma helicopters following the discovery of metal fatigue in the gearbox of a Super Puma that fatally crashed in Norway on April 29.

The flight ban was announced after Norway's Civil Aviation Authority earlier extended its ban on flying the aircraft to include search and rescue missions.

The Super Pumas, a workhorse of the offshore oil industry, were banned from commercial traffic in Norway and Britain following the accident, but hitherto search and rescue missions had still been allowed.

"EASA has decided to prohibit all flights by the Airbus H225 LP and AS332 L2 helicopters as a precautionary measure and until further information is available," EASA said in a statement.

In the April 29 crash the H225 Super Puma's main rotor blades separated from the aircraft as it was ferrying passengers from a Norwegian offshore oil platform operated by Statoil (Hamburg: 1245893.HM - news) . All 13 people on board were killed.

The findings were published in a preliminary report by Accident Investigation Board Norway (AIBN) on Wednesday, which urged EASA to take immediate action to ensure the safety of the helicopter's main gearbox.

Statoil (LSE: 0M2Z.L - news) said in a separate statement it would find other ways of operating its emergency services for the Oseberg Field Centre and Statfjord B platforms in the North Sea.

"Statoil is currently mobilizing the necessary resources to safeguard preparedness requirements," the company said.

The helicopter that crashed in April was working for the Norwegian firm and operated by Canadia-based group CHC Helicopter.

CHC said it welcomed the latest report from the AIBN and that it had suspended all flights by the H225 aircraft as a result, even before the Norwegian ban was announced.

Airbus Helicopters declined to comment further as the investigation continues, a spokesman said on Thursday.

Investigators have ruled out human error, saying the crash was caused by a technical fault.

On Wednesday the AIBN said it had found metallurgical evidence "strongly consistent with fatigue" in a part of the gearbox, while adding it was focusing simultaneously on several different scenarios for the crash.

Previous Super Puma incidents linked to gearbox problems included a 2009 crash off Peterhead, Scotland, in which the rotor also flew off and 16 people died.

Airbus Helicopters told operators in a bulletin this week that there were "significant elements" differing from the 2009 crash, according to a copy seen by Reuters.

It (Other OTC: ITGL - news) placed most emphasis on a possible failure of one of the struts holding the rotors to the aircraft, saying that could have been caused by either faulty bolts or missing safety pins.

Design and production are the responsibility of Airbus Helicopters; maintenance is handled by CHC. (Reporting by Terje Solsvik and Stine Jacobsen in Oslo, Victoria Bryan in Dublin and Cyril Altmeyer in Paris, Georgina Prodhan and Jonathan Gould in Frankfurt; Editing by Richard Pullin, Greg Mahlich)