[Federal Register Volume 60, Number 138 (Wednesday, July 19, 1995)]
[Rules and Regulations]
[Pages 36974-36976]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-17709]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 93-NM-122-AD; Amendment 39-9314; AD 94-21-05 R1]
Airworthiness Directives; Boeing Model 737-300, -400, and -500
Series Airplanes Equipped With CFM International CFM56-3 Series Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; correction.
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SUMMARY: This amendment clarifies an existing airworthiness directive
(AD), applicable to certain Boeing Model 737-300, -400, and -500 series
airplanes, that currently requires modification, adjustments, and tests
of the thrust reverser system; and repair, if necessary. This amendment
clarifies a requirement specified in the AD concerning the performance
of the operational test of the system. This amendment is prompted by an
inquiry from an operator of the affected airplanes concerning that
aspect of the existing AD.
DATES: Effective November 25, 1994. -
The incorporation by reference of certain publications listed in
the regulations was approved by the Director of the Federal Register as
of November 25, 1994 (59 FR 53573, October 25, 1994).
ADDRESSES: The service information referenced in this AD may be
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,
Washington 98124-2207. This information may be examined at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue SW., Renton,
Washington; or at the Office of the Federal Register, 800 North Capitol
Street NW., suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Stephen Bray, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification
Office, 1601 Lind Avenue, SW., Renton, Washington; telephone (206) 227-
2681; fax (206) 227-1181.
SUPPLEMENTARY INFORMATION: On October 6, 1994, the FAA issued AD 94-21-
05, amendment 39-9047 (59 FR 53573, October 25, 1994), applicable to
certain Boeing Model 737-300, -400, and -500 series airplanes, to
require modification, adjustments, and tests of the thrust reverser
system; and repair, if necessary. The actions required by that AD are
intended to prevent deployment of a thrust reverser in flight and
subsequent reduced controllability of the airplane. -
Since the issuance of that AD, the FAA has received an inquiry from
an operator of the affected airplanes concerning the requirement of
paragraph (d)(2) of the AD. That paragraph requires deactivation of a
thrust reverser if a discrepancy is found during accomplishment of the
thrust reverser sync-lock integrity test. The last sentence of
paragraph (d)(2) specifies that, following deactivation of the
associated thrust reverser, ``the sync-locks installed on the
deactivated thrust reverser must remain operational.'' The operator
questions how the sync-lock can remain ``operational'' when the thrust
reverser has been deactivated for failing the required integrity test.
-
The FAA finds that clarification of the term ``operational'' is
necessary. The FAA's intent in specifying that the sync-lock remain
operational was actually to require that it be verified to be in the
locked position. In order to avoid unnecessary flight delays and
cancellations, the FAA included the provision contained in paragraph
(d)(2) of AD 94-21-05 to provide relief to allow dispatch of the
airplane with deactivated sync-locks, in accordance with provisions and
limitations contained in the Master Minimum Equipment List (MMEL). This
relief involves locking out a thrust reverser and verifying that the
failed sync-lock is deactivated and in the locked position. In light of
this, action is taken herein to revise AD 94-21-05 to clarify paragraph
(d)(2) of the AD accordingly. There are no other changes to the rule. -
The final rule is being reprinted in its entirety for the
convenience of affected operators. The effective date remains November
25, 1994. -
Since this action only clarifies a requirement of a final rule, it
has no adverse economic impact and imposes no additional burden on any
person. Therefore, notice and public procedures hereon are unnecessary.
List of Subjects in 14 CFR Part 39 -
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment -
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation
[[Page 36975]]
Administration amends part 39 of the Federal Aviation Regulations (14
CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES -
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended] -
2. Section 39.13 is amended by removing amendment 39-9047 (59 FR
53573, October 25, 1994), and by adding a new airworthiness directive
(AD), amendment 39-9314, to read as follows:
94-21-05 R1 Boeing: Amendment 39-9314. Docket 93-NM-122-AD. Revises
AD 94-21-05, Amendment 39-9047.
-Applicability: Model 737-300, -400, and -500 series airplanes
equipped with CFM International CFM56-3 series engines, certificated
in any category. -
Compliance: Required as indicated, unless accomplished
previously.
To prevent deployment of a thrust reverser in flight and
subsequent reduced controllability of the airplane, accomplish the
following:
(a) For airplanes on which the sync-lock installation [specified
in paragraph (b) of this AD], sync-lock wiring modification
[specified in paragraph (c) of this AD], or Production Revision
Record (PRR) 35105 has not been accomplished: Within 60 days after
the effective date of this AD, and thereafter at intervals not to
exceed 4,000 hours time-in-service, perform adjustments and tests of
the thrust reverser system that are specified in Section 78-31-00 of
the Boeing 737 Maintenance Manual to verify proper operation of the
thrust reverser system, in accordance with that section of the
maintenance manual. If any discrepancy is found, prior to further
flight, accomplish either paragraph (a)(1) or (a)(2) of this AD.
(1) Repair any discrepancy found, in accordance with procedures
described in the Boeing 737 Maintenance Manual. Or
(2) Deactivate the associated thrust reverser in accordance with
the existing provisions and limitations specified in the Master
Minimum Equipment List (MMEL).
(b) For airplanes on which the sync-lock feature was not
installed during production or as a modification in accordance with
Boeing Service Bulletin 737-78-1053, dated December 17, 1992: Within
5 years after the effective date of this AD, install an additional
thrust reverser system locking feature (sync-lock installation) in
accordance with Boeing Service Bulletin 737-78-1053, Revision 1,
dated July 1, 1993; Revision 2, dated February 17, 1994; or Revision
3, dated June 30, 1994. Installation of the additional locking
feature constitutes terminating action for the tests required by
paragraph (a) of this AD.
(c) For airplanes listed in Boeing Service Bulletin 737-78-1058,
dated July 1, 1993: Within 5 years after the effective date of this
AD, modify the sync-lock wiring in accordance with Boeing Service
Bulletin 737-78-1058, dated July 1, 1993; Revision 1, dated February
17, 1994; or Revision 2, dated July 7, 1994. Modification of the
sync-lock wiring constitutes terminating action for the tests
required by paragraph (a) of this AD.
(d) At the times specified in paragraph (e) of this AD,
accomplish the ``Thrust Reverser Sync-Lock Integrity Test''
specified below to verify that the sync-locks are not failing in the
unlocked state. If any discrepancy is found, prior to further
flight, accomplish paragraph (d)(1) or (d)(2) of this AD.
(1) Repair any discrepancy found, in accordance with procedures
specified in the Boeing 737 Maintenance Manual. Or
(2) Deactivate the associated thrust reverser in accordance with
the existing provisions and limitations specified in the MMEL; and
verify that the failed sync-lock is deactivated and in the locked
position.
``THRUST REVERSER SYNC-LOCK INTEGRITY TEST
1. General
A. Use this procedure to test the integrity of the thrust reverser
sync-locks. -
The procedure must be performed on each engine.
2. Thrust Reverser Sync-Lock Test
A. Prepare for the Thrust Reverser Sync-Lock test.
(1) Do the steps that follow to supply power to the thrust
reverser -system:
(a) Make sure the thrust levers are in the idle position.
(b) Make sure the thrust reversers are retracted and locked.
(c) Make sure these circuit breakers on the P6 circuit breaker
panel are closed:
(1) ENGINE 1 THRUST REVERSER CONT SYS
(2) ENGINE 2 THRUST REVERSER CONT SYS
(3) ENGINE 2 THRUST REVERSER CONT -SYS-ALT
(4) ENGINE 1 THRUST REVERSER IND SYS
(5) ENGINE 2 THRUST REVERSER IND SYS
(6) ENGINE 1 SYNC-LOCK
(7) ENGINE 2 SYNC-LOCK
(8) ENGINE 2 SYNC-LOCK-ALTN
(9) LANDING GEAR AIR/GND RELAY AND LIGHTS
(10) RADIO ALTM-2
(d) Make sure this circuit breaker on the P18 circuit breaker
panel is closed:
(1) RADIO ALTM-1
(e) Supply electrical power.
(f) Remove pressure from the A (for the left engine) or B (for
the right engine) hydraulic system.
B. Do the thrust reverser sync-lock test.
(1) Move and hold the manual unlock lever on the upper actuator
on -both thrust reverser sleeves to the unlock position.
(2) Make sure the thrust reverser sleeves did not move aft.
(3) Move the left (right) reverse thrust lever up and rearward
to the -reverse thrust position.
(4) Make sure both thrust reverser sleeves move aft
(approximately -0.15 to 0.25 inch).
(5) Release the manual unlock lever on the upper actuators.
WARNING: MAKE SURE ALL PERSONS AND EQUIPMENT ARE CLEAR OF THE
AREA AROUND THE THRUST REVERSER. WHEN YOU APPLY HYDRAULIC PRESSURE,
THE THRUST REVERSER WILL EXTEND AND CAN CAUSE INJURIES TO PERSONS OR
DAMAGE TO EQUIPMENT.
(6) Pressurize the A (B) hydraulic system.
(7) Make sure the thrust reverser extends.
(8) Move the left (right) reverse thrust lever to the forward
and down -position to retract the thrust reverser.
C. Put the airplane back to its usual condition.
(1) Remove hydraulic pressure.
(2) Remove electrical power.
D. Repeat the thrust reverser sync-lock test on the other engine.''
(e) Accomplish the test required by paragraph (d) of this AD at
the times specified in paragraph (e)(1) or (e)(2) of this AD, as
applicable.
(1) For airplanes that are subject to the requirements of
paragraphs (b) and (c) of this AD: Within 4,000 hours time-in-
service after accomplishing the modification required by paragraph
(b) or (c) of this AD, as applicable, or within 4,000 hours time-in-
service after the effective date of this AD, whichever occurs later;
and thereafter at intervals not to exceed 4,000 hours time-in-
service.
(2) For all other airplanes: Within 4,000 total hours time-in-
service, or within 4,000 hours time-in-service after the effective
date of this AD, whichever occurs later; and thereafter at intervals
not to exceed 4,000 hours time-in-service.
(f) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Seattle Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Seattle ACO.
Note: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(g) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
(h) The installation and wiring modification shall be done in
accordance with Boeing Service Bulletin 737-78-1053, Revision 1,
dated July 1, 1993; Boeing Service Bulletin 737-78-1053, Revision 2,
dated February 17, 1994; Boeing Service Bulletin 737-78-1053,
Revision 3, dated June 30, 1994; Boeing Service Bulletin 737-78-
1058, dated July 1, 1993; Boeing Service Bulletin 737-78-1058,
Revision 1, dated February 17, 1994; or Boeing Service Bulletin 737-
78-1058, Revision 2, dated July 7, 1994. The incorporation by
reference of this document was approved by the Director of the
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part
51 as of November 25, 1994 (59 FR 53573, October
[[Page 36976]]
25, 1994). Copies may be obtained from Boeing Commercial Airplane
Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be
inspected at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue SW., Renton, Washington; or at the Office of the Federal
Register, 800 North Capitol Street NW., suite 700, Washington, DC.
(i) This amendment is effective on November 25, 1994.
Issued in Renton, Washington, on July 13, 1995.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-17709 Filed 7-18-95; 8:45 am]
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