Aims To Prevent Widespread Fatigue Damage -- But Operators
Would Have To Pay
Earlier this week, the
FAA issued its Notice for Proposed Rulemaking (NPRM) on measures
the agency intends to prevent fatigue damage in transport category
aircraft. The proposal would require aircraft manufacturers and
design approval holders to establish operational limits on
transport category airplanes, in order to prevent widespread
fatigue damage (WFD.) Those parties would also be required to
determine if maintenance actions are needed to prevent widespread
fatigue damage before an airplane reaches its operational
limit.
Operators of any affected airplane would be required to
incorporate the operational limit, and any necessary service
information, into their maintenance programs. Operation of an
affected airplane beyond the operational limit would be prohibited,
unless an operator has incorporated an extended operational limit
and any necessary service information into its maintenance
program.
The FAA states the proposal should preclude WFD from occurring
in transport category airplanes, by providing a "more proactive
management" of WFD.
The proposal would also require type certificate (TC) holders to
establish an initial operational limit on certain airplanes.
Operation of these airplanes beyond the initial operational limit
would be prohibited, unless operators incorporated an extended
operational limit into their maintenance programs.
The FAA states that present value benefits of the proposal
consist of $726 million of accident prevention benefits, and $83
million of detection benefits -- for total benefits of $809
million. The detection benefits the FAA cites are the benefits
resulting from accidents averted by the measure if it is
implemented -- accidents that haven't occurred yet, in other words
-- and a reduction in unscheduled maintenance and repairs.
The present value cost of this proposal, estimated over 20
years, is $360 million. Here's the kicker, however: the FAA
estimates that airplane manufacturers would incur approximately 10
percent of these costs -- while the remaining 90 percent of these
costs would be borne by operators.
Type certificate holders would be required to develop the
initial operational limits based on an evaluation of WFD
susceptibility, both for existing airplanes and for proposed future
certifications. For future type certification, all TC applicants
for transport category airplanes would be affected.
As far as existing type certificates, the proposal would affect
only airplanes with maximum takeoff gross weights (MTGW) over
75,000 pounds, including airplanes that have had the MTGW increased
to greater than 75,000 pounds.