flaps2billion wrote:
Yes clearly a failed filter caused the O-ring to magically appear in the hydraulic actuator.........
From the
Preliminary Report, dated 03-11-2007:
The physical dimensions of the rogue O-Ring was similar to that of the NAS1611-110 O-Ring identified on the drawings for the door solenoid sequence valve (SSV). It was further determined that the only component in the landing gear system that incorporated this O-Ring was the SSV.
A review of the maintenance history identified that an SSV on the right main landing gear system had been replaced on 16 October 2007. This component was located and examined. The examination revealed that a filter element and an O-Ring were not present in the down port in the SSV.
To establish similarity with the rogue O-Ring, an O-Ring was removed from a second SSV and was examined. They were found to be identical in both size and in material composition.
In the course of this investigation, the Danish AIB became aware that past occurrences showed that filter elements in the SSV can collapse and migrate into the landing gear hydraulic system. In the past occurrences, O-Rings (situated adjacent to the filter) from the SSVīs are not known to have migrated into the landing gear hydraulic system.
However it is the conclusion of the Danish AIB, that the O-ring found blocking the right main landing gear actuator restrictor valve, was from the SSV that was previously installed on the occurrence aircraft.
Not much magic involved here, me thinks...
flaps2billion wrote:
"Bombardier has up to now banked on a preliminary report from the Danish Accident Investigation Commission, where it says that SAS mechanics had used parts for the rear of the landing gear that were intended for the nose portion."
BBD 1, SAS 0
From the same report:
A further review of the maintenance history revealed that the MSV (mechanical sequence valve) of the right main landing gear was replaced on 22 October 2007.
According to the maintenance records, the replacement MSV, supplied, was a P/N 48303-7 which was initially configured for installation into the nose landing gear hydraulic system. Prior to installation on the occurrence aircraft, the supplied MSV was reconfigured by maintenance personnel. To make the MSV P/N 48303-7 compatible with the installation requirements for the main landing gear, the unions from the replaced MSV P/N 48303-5 were used.
In other words, an identical part, with identical functions, but with different external fittings on it, as indicated by the different dash-number on the part...