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NTSB SAFETY RECOMMENDATION
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National Transportation Safety Board
Washington, DC 20594

August 28, 2006

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Safety Recommendation A-06-60 through A-06-64

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The National Transportation Safety Board
recommends that the Federal Aviation
Administration:

Require that all CF6-80A and -80C2 high
pressure turbine (HPT) stage 1 disks and
applicable -80E1 HPT stage 1 disks that have
more than 3,000 cycles since new (CSN) and
have not been reworked in accordance with
General Electric Service Bulletins (SB) 72-
0788 or 72-1089 or have not yet been
inspected in accordance with SB 72-0779 or
Alert Service Bulletin 72-A1026 be
immediately removed from service for
inspection and rework in accordance with
these SBs. Those CF6-80A and -80C2 HPT stage
1 disks and applicable -80E1 HPT stage 1
disks that have fewer than 3,000 CSN and have
not been reworked or inspected in accordance
with these SBs can remain in service until
reaching the 3,000 CSN threshold, at which
time they should also be removed from service
for inspection and rework. (A-06-60) Urgent

Require that all CF6-80A and -80C2 high
pressure turbine (HPT) stage 1 disks and
applicable -80E1 HPT stage 1 disks that have
not been reworked in accordance with General
Electric Service Bulletins (SB) 72-0788 or 72-
1089 but have been inspected in accordance
with SB 72-0779 or Alert Service Bulletin
(ASB) 72-A1026 and have more than 3,000
cycles since the inspection be immediately
removed from service for reinspection and
rework in accordance with these SBs. Those
CF6-80A and -80C2 HPT stage 1 disks and
applicable -80E1 HPT stage 1 disks that have
not been reworked in accordance with SBs 72-
0788 or 72-1089 but have been inspected in
accordance with SB 72-0779 or ASB 72-A1026
and have fewer than 3,000 cycles since the
inspection can remain in service until
reaching the 3,000 cycles-since-inspection
threshold, at which time they should also be
removed from service for reinspection and
rework. (A-06-61) Urgent

Revise the engine-related airworthiness
directive process to ensure that the
compliance timelines are appropriately
established. (A-06-62)

Require a design review of CF6-80 series high
pressure turbine (HPT) stage 1 disks that
incorporate chamfered blade slot bottom aft
corners that includes a stress analysis and
finite element model emphasizing the blade
slot bottom aft corner to determine whether
sufficient material property margin exists to
ensure that cracks do not occur. If the
design review of chamfered HPT stage 1 disks
finds that this design does not provide
sufficient material property margin, then a
redesign or material change should be
implemented. (A-06-63)

Require that maintenance personnel ensure
that an aircraft's cockpit voice recorder
(CVR) is operating before conducting any
engine ground tests. If an airplane has been
involved in a reportable event, the incident
CVR should be removed to preserve the event
data and any subsequent ground test should be
delayed until a suitable replacement CVR can
be installed in the aircraft. (A-06-64)


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http://www.ntsb.gov/recs/letters/2006/A06_60_64.pdf

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