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NTSB Safety Recommendation A-06-60 through -64



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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 A06-60-64

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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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The complete recommendation letter is available on
the Web at the URL indicated above.

The letter is in the Portable Document Format(PDF) 
and can be read using the Acrobat Reader 3.0 or later from Adobe
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An archive of recommendation letters is available
At http://www.ntsb.gov/recs/letters/letters.htm.
Please note that the electronic version of this letter may
not include enclosures; however, related publications,
accident briefs, and aviation accident synopses are also
available on the web site.

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