AD NUMBER: 2009-23-07

MANUFACTURER: Saab AB, Saab Aerosystems Model SAAB 340A (SAAB/SF340A) and SAAB 340B Airplanes
SUBJECT: Airworthiness Directive 2009-23-07

SUMMARY: This AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

During 2008, two cases of main hydraulic accumulator failure were 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 aeroplane 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.

FMI: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/88FCD907D5A469AA862576690053E908?OpenDocument