Document ID: chunk:federal_register_of_legislation:F2009L03072:body:0:p2
Version: federal_register_of_legislation:F2009L03072
Segment Type: other
Provision Reference: 
Character Range: 2735–4507

been reported, one of which was caused by corrosion.  Investigation has shown that a severe failure can occur to any of the four hydraulic accumulators which are installed in the hydraulic compartment.  Either one of the two end parts on the accumulator may depart from the pressure vessel due to corrosion.  This condition, if not corrected, is likely to degrade the functionality of the hydraulic system, possibly resulting in degradation or total loss of control of the landing gear, flap actuation and brakes.

             A severe failure during flight may even result in debris penetrating and exiting the fuselage outer skin.  When such a failure occurs while the aircraft is on the ground, as in the two reported cases, this may cause severe damage to the fuselage and result in injuries to persons nearby.

             To address and correct the unsafe condition, a modified hydraulic accumulator has been developed, which is sealed between the barrel and the screw cap and between the screw cap and the end cap.

             For the reasons described above, this AD requires the replacement of the affected hydraulic accumulators P/N 08 8423 001 1 and P/N 08 8423 030 1, as identified in SAAB SB 340-29-023, with a modified hydraulic accumulator.

             Since the original issue of this AD, one more case of main hydraulic accumulator failure has been reported, which occurred in flight during final approach.  The aeroplane was able to land safely and there were no injuries reported on the aeroplane or on the ground.

             This amendment corrects the compliance date from 15 September 2008 to
             25 September 2008 with no change to the requirements.

James Coyne
Delegate of the Civil Aviation Safety Authority

15 July 2009