HELICOPTER manufacturers Airbus knew about issues with the EC135 model's fuel readings a decade before the Clutha crash.

A Fatal Accident Inquiry (FAI) at Hampden Park was shown emails from June 2003 to the company that showed complaints about water in helicopters' engines.

Ralf Nicolai, sales promotion manager at Airbus Helicopters Deutschland, is giving evidence at the inquiry in front of Sheriff Principal Craig Turnbull.

The inquiry seeks to find out answers as to why Police Scotland helicopter G-SPAO crashed through the roof of the Clutha Vaults on November 29, 2013.

Ten people were killed - including three helicopter crew - and 31 people were injured.

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Airbus designs, manufactures and delivers aircraft and were the manufacturers of G-SPAO.

The Clutha helicopter had five low fuel warnings before it crashed in Glasgow.

A low fuel warning, the court has previously been told, should prompt a pilot to land within eight to 10 minutes but pilot David Traill continued to carry out operations to the east of Glasgow following the warnings.

In 2003, Airbus had been made aware of issues with fuel readings in its EC135 helicopters and this was suspected to have been caused by water rusting the HMU, part of the fuel system.

It later became clear, the court heard, that water was causing problems with the fuel level sensors.

The court also heard that on June 8, 2015, Airbus convened a Reliability Data Group with its customers from across Europe, including Switzerland's Air Zermatt, Bond Air Services in England and Norwegian Air Ambulance, among others.

Airbus had created a website where customers could enter any faults occurring on their helicopters.

But information was limited and helicopter owners could not add specific notes to the entries so additional data was given at the Reliability Data Group.

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The 2015 group heard of no issues with fuel sensors.

Mr Nicolai said: "It has never been identified in any reliability data."

Procurator Fiscal Depute Sean Smith QC asked him: "Would you have expected it to?"

Mr Nicolai replied: "Looking at it now, I don't think we would have detected it because it has [gone unnoticed] by any customers.

"We have this particular situation here in the UK where engines have to be washed every day because the UK is a corrosive environment."

The court heard the environment in which an aircraft flies is designated corrosive or erosive, where erosion involves sand getting into the engine.

The UK was designated corrosive, which meant engines had to be washed every day to protect them from damage.

The court heard this could lead to water getting in to fuel sensors and causing over-readings in the sensor.

The inquiry has previously been told how on December 11, 2013, an air ambulance landed at City Airport, Manchester, with the pilot reporting contradictory fuel readings and low fuel warnings.

Bond, the aircraft operator, grounded its fleet to carry out tests.

Later, Donald Findlay, representing the family of victim Robert Jenkins, questioned Mr Nicolai. He said: "For 10 years there has been some kind of issue with water and fuel which was, at the time of the crash, unresolved.

"People might want to know why, after 10 years and only after people died and the incident in the Manchester fleet, was a full investigation carried out."

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In the afternoon the court heard evidence from Christian Bernhardt, a safety investigator with Airbus.

He is expected to give evidence again today in front of Sheriff Principal Craig Turnbull.

Pilot David Traill, 51; PC Tony Collins, 43; and PC Kirsty Nelis, 36, died along with seven customers who were in the bar, Gary Arthur, 48; Joe Cusker, 59; Colin Gibson, 33; Robert Jenkins, 61; John McGarrigle, 58; Samuel McGhee, 56; and Mark O'Prey, 44.