Judge Juan Javier Perez is investigating the head of Spanair's maintenance staff and two mechanics for 'manslaughter and injuries caused by carelessness', the source said.

They have been summoned to attend a first hearing on November 12.

The McDonnell Douglas-82, on a flight to the Canary Islands, crashed moments after taking off from Madrid airport on August 20. Only 18 of the 172 people aboard survived Spain's deadliest air accident in 25 years.

The chief pilot had aborted an earlier takeoff attempt because of a faulty temperature gauge on an air intake valve, a problem that was fixed by the mechanics prior to the ill-fated takeoff.

Judge Perez hopes to discover if these repairs somehow contributed to the accident.

A report released last week into the crash said the wing flaps were not properly extended on takeoff and an alarm failed to alert the pilots to the problem.

The problem with the temperature gauge may have been 'the consequence or the manifestation of a multifunctional failure that could also have affected the faulty alarm system for the takeoff,' the judge said.

He noted the gauge was connected to 'the same electrical system' as the faulty alarm for the wing flaps.

The head of the maintenance team could 'be responsible for the inadequate repairs to the plane,' he said.

The preliminary investigation report was compiled by a team set up by Spain's CIAIAC air accident investigation committee.

The judicial source said Judge Perez had ordered a second investigation commission to be formed, comprising two pilots, two engineers and two mechanics, all with at least 15 years experience.

On Wednesday, he heard testimony from two policemen who went to the scene of the crash. In the coming days he will hear rescue workers and other people directly affected by the disaster.

The CIAIC report said the plane, lacking the necessary lift from the wing flaps, managed to climb just 12 metres before tilting slightly to the left and then hard to the right and crashing to the ground tail-first.

'Throughout the take-off approach and until the end of the (black box) recording, there was no sound from the alarm system indicating an inappropriate setting for take-off,' it said.

A first draft of the report leaked earlier said the crash could have been avoided if the airline had followed the recommendations of the Boeing Corporation, which owns McDonnell Douglas, issued after an accident involving the same type of aircraft in Detroit, Michigan, in 1987.

'The (Spanair) service manual in use at the time of the accident calls for this check (of the alarm system) before the first flight of the day and on stops between flights, unless at least one of the two pilots remains on duty,' said the pre-report.

Boeing's more stringent recommendation is that the check be carried out 'before every flight, without exception'. However, this section was erased from the version released last week, after Spanair said the leaked extracts contained 'imprecisions'.

The airline's director of operations, Mr Javier Muela, said Boeing made the recommendation one year before Spanair, a unit of Scandinavian carrier SAS, was set up in 1988 and it was not informed by the planemaker of the need to verify the alarm. -- AFP