AD NUMBER: 2008-03-21
SUBJECT: Airworthiness Directive 2008-03-21 SUMMARY: We are adopting a
new airworthiness directive (AD) for the products listed above.
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: * * * * * Recently, it
was discovered that the inspection procedure as described by Fokker
50 Non-Destructive Testing Manual (NDTM), Part 6, Chapter 53-30-02,
which is referenced by Fokker 50 Maintenance Review Board (MRB)
Tasks Number 530000-00-04 and 530000-00-08 [currently required per
AD (BLA) 2002-061], did not show the correct inspection areas. In
addition to the existing procedure, the area at the kink in the
bottom fuselage skin, the actual chine line, must be inspected.
Investigation revealed that a number of aircraft have already
passed the relevant inspection thresholds of 20,000 and 45,000
flight cycles by a considerable margin. As a result, it may be
possible that cracks have developed and remained undetected. * * *
* * * * * The unsafe condition is cracking and subsequent failure
of the fuselage bottom skin, which could result in reduced
structural integrity of the fuselage. This AD requires actions that
are intended to address the unsafe condition described in the