[Federal Register Volume 62, Number 3 (Monday, January 6, 1997)]
[Rules and Regulations]
[Pages 604-607]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-161]



[[Page 604]]

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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-273-AD; Amendment 39-9866; AD 96-26-03]
RIN 2120-AA64


Airworthiness Directives; Fokker Model F28 Mark 0070 and 0100 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to all Fokker Model F28 Mark 0070 and 0100 series 
airplanes, that currently requires a revision to the Airplane Flight 
Manual (AFM) that will enable the flightcrew to determine if the thrust 
reversers are properly stowed and locked prior to take-off. In 
addition, the existing AD requires a revision to the maintenance 
program to incorporate instructions to perform checks of the thrust 
reverser system and correct thrust reverser malfunctions. That AD was 
prompted by results of a review, which indicated that a potential 
latent failure of the secondary lock actuator switch 1 of the thrust 
reverser system in the open position may occur, in addition to the 
potential failure of the secondary lock relay 1 in the energized 
position. This new AD adds a requirement to accomplish new 
modifications that will serve as terminating actions for the revisions 
to the AFM and maintenance program, and new repetitive checks of the 
thrust reverser system. The actions specified in this AD are intended 
to ensure protection against inadvertent deployment of the thrust 
reversers during flight.

DATES: Effective January 21, 1997.
    The incorporation by reference of Fokker Service Bulletin SBF100-
78-012, dated November 22, 1996; Fokker Service Bulletin SBF100-24-034, 
Revision 1, dated September 12, 1996; and Fokker Service Bulletin 
SBF100-78-013, dated November 22, 1996; as listed in the regulations; 
is approved by the Director of the Federal Register as of January 21, 
1997.
    The incorporation by reference of Fokker All Operator Message 
TS96.67591, dated November 14, 1996, was approved previously by the 
Director of the Federal Register as of December 24, 1996 (61 FR 66890, 
December 19, 1996).
    Comments for inclusion in the Rules Docket must be received on or 
before March 7, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-273-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    The service information referenced in this AD may be obtained from 
Fokker Service B.V., Technical Support Department, P. O. Box 75047, 
1117 ZN Schiphol Airport, The Netherlands. 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: Tim Dulin, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2141; fax (206) 227-1149.

SUPPLEMENTARY INFORMATION: On December 5, 1996, the FAA issued AD 96-
24-10, amendment 39-9850 (61 FR 66890, December 19, 1996), applicable 
to all Fokker Model F28 Mark 0070 and 0100 series airplanes. That AD 
superseded AD 96-23-16, amendment 39-9825 (61 FR 5887, November 20, 
1996). AD 96-24-10 requires a revision to the Limitations Section of 
the FAA-approved Airplane Flight Manual (AFM) to enable the flightcrew 
to determine if the thrust reversers are properly stowed and locked 
prior to take-off by monitoring proper engagement of the autothrottle 
system (ATS). It also allows dispatch of the airplane with both thrust 
reversers inoperative provided they are deactivated and secured in the 
stowed position, and no operations are conducted that are predicated on 
thrust reverser operation. In addition, that AD requires a revision to 
the FAA-approved maintenance program to incorporate instructions to 
correct malfunctions of the secondary lock relay 1 of the thrust 
reversers found during the operational tests; to perform a daily check 
to detect latent failure of the secondary lock actuator switch 1; and 
to take corrective actions, if necessary.
    That action was prompted by results of a review and safety 
assessment of the thrust reverser control and indication system, which 
indicated that a potential latent failure of the secondary lock 
actuator switch 1 in the open position may occur in addition to the 
potential failure of the secondary lock relay 1 in the energized 
position addressed by AD 96-23-16.
    The actions required by AD 96-24-10 are intended to prevent such 
failures, which could result in reduced protection against inadvertent 
deployment of the thrust reversers during flight.
    In the preamble to AD 96-24-10, the FAA indicated that the actions 
required by that AD were considered to be ``interim action'' and that 
further rulemaking action was being considered. The FAA now has 
determined that further rulemaking action is indeed necessary, and this 
AD follows from that determination.

New Service Information from the Manufacturer

    Fokker issued Service Bulletin SBF100-78-012, dated November 22, 
1996, which describes procedures for modification of the wiring of the 
electrical control, and indication and warning systems of the thrust 
reversers. This modification involves changing the wiring of the stow 
limit relay of the thrust reverser, which will prevent inadvertent loss 
of the thrust reverser stow signal during certain failure conditions 
(i.e., bypasses the stow limit relay to ensure that the stow solenoid 
is energized at all times regardless of the position of the secondary 
lock actuator switch 1, except during commanded deployment of the 
thrust reverser). This modification also involves changing the wiring 
of the flight warning computer (FWC), which will prevent unintended 
inhibition of the thrust reverser warning (i.e., bypasses the warning 
switch of the secondary lock relay 1). Accomplishment of this 
modification will eliminate the need for the revisions to the AFM and 
maintenance program (currently required by AD 96-24-10).
    In addition, accomplishment of this modification will slightly 
increase the electrical loads on the emergency direct current (DC) bus 
on Fokker Model F28 Mark 0070 and 0100 series airplanes. The load 
margin for Fokker Model F28 Mark 0100 series airplanes is adequate to 
sustain the additional electrical loads created by accomplishment of 
Service Bulletin SBF100-78-012; however, Fokker Model F28 Mark 0070 
series airplanes do not have an adequate load margin to sustain these 
additional loads. Therefore, Fokker Service Bulletin SBF100-24-034, 
Revision 1, dated September 12, 1996, must be accomplished on Fokker 
Model F28 Mark 0070 series airplanes prior to or in conjunction with 
Fokker Service Bulletin SBF100-78-012. Fokker Service Bulletin SBF100-
24-034 describes procedures for modification of the wiring of the 
priority switching of the emergency inverter power supply. The 
modification involves reconfiguring the emergency DC bus wiring. 
Accomplishment of this modification

[[Page 605]]

will reduce the load of the emergency DC bus on Fokker Model F28 Mark 
0070 series airplanes.
    In addition, Fokker has also issued Service Bulletin SBF100-78-013, 
dated November 22, 1996. This service bulletin describes procedures for 
performing repetitive operational checks to detect failures of the 
secondary lock actuator, primary lock switch, indication and warning 
system, and feedback cable mechanism of the thrust reversers; and 
repair of the thrust reverser system, if necessary.
    The Rijksluchtvaartdienst (RLD), which is the airworthiness 
authority for the Netherlands, classified these service bulletins as 
mandatory and issued Dutch airworthiness directive BLA 1996-140 (A), 
dated November 25, 1996, in order to assure the continued airworthiness 
of these airplanes in the Netherlands.

FAA's Conclusions

    These airplane models are manufactured in the Netherlands and are 
type certificated for operation in the United States under the 
provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 
21.29) and the applicable bilateral airworthiness agreement. Pursuant 
to this bilateral airworthiness agreement, the RLD has kept the FAA 
informed of the situation described above. The FAA has examined the 
findings of the RLD, reviewed all available information, and determined 
that AD action is necessary for products of this type design that are 
certificated for operation in the United States.

Explanation of Requirements of the New Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, this AD supersedes AD 96-24-10. It continues to 
require the following actions:
     A revision to Limitations Section of the FAA-approved AFM 
that will enable the flightcrew to determine if the thrust reversers 
are properly stowed and locked prior to take-off by monitoring proper 
engagement of the authothrottle system (ATS); and
     A revision to the FAA-approved maintenance program to 
incorporate instructions to correct malfunctions found during the 
operational tests of the secondary lock relay 1 of the thrust 
reversers; to perform a daily check to detect latent failure of the 
secondary lock actuator switch 1; and to take corrective actions, if 
necessary.
    In addition, this AD requires performing the following new 
requirements:
    1. Modification of the wiring of the electrical control, and 
indication and warning systems of the thrust reversers, which 
terminates the currently required AFM revision and the maintenance 
program revision;
    2. Modification of the wiring of the priority switching of the 
emergency inverter power supply, for certain airplanes;
    3. Repetitive operational checks to detect failures of the 
secondary lock actuator, primary lock switch, indication and warning 
system, and feedback cable mechanism of the thrust reversers; and 
repair of the thrust reverser system, if necessary; and
    4. Submission of a report of any finding to Fokker following 
accomplishment of the operational checks.
    These actions are required to be accomplished in accordance with 
the service bulletins described previously.
    Operators should note that the FAA has deleted the previous 
allowance to dispatch with both thrust reversers inoperative, which was 
specified in paragraph (b) of AD 96-24-10. The FAA finds that such an 
allowance is unnecessary, since adequate spare parts are now available 
to accomplish any required part replacements as a result of the daily 
maintenance check.

Difference Between the AD and the Related Dutch AD

    This AD differs from the Dutch airworthiness directive BLA 1996-140 
(A) in that it does not address changes to the FAA Master Minimum 
Equipment List (MMEL), whereas the Dutch airworthiness directive 
changes the requirements of the Dutch MMEL for the autothrottle and the 
thrust reverser indication and alerting system. The Dutch BLA allows 
dispatch with both autothrottle channels inoperative and both thrust 
reverser indication and alerting systems inoperative provided both 
thrust reversers are deactivated and secured in the stowed position, 
and no operations or procedures are predicated on their use. The FAA 
MMEL only allows dispatch with one autothrottle channel inoperative and 
does not allow dispatch with either thrust reverser indication or 
alerting system inoperative. The FAA finds no safety-related reason to 
relax these requirements.

Interim Action

    This is considered to be interim action. The exact cause of the 
addressed unsafe condition is still unknown at this time. The reports 
of operational check results that are required by this AD will enable 
the manufacturer to obtain better insight into the nature, cause, and 
extent of the inadvertent thrust reverser deployment, and eventually to 
develop final action to address the unsafe condition. Once final action 
has been identified, the FAA may consider further rulemaking.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications shall identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 96-NM-273-AD.'' The postcard will be date stamped and 
returned to the commenter.

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Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

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 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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-9850 (61 FR 
66890, December 19, 1996), and by adding a new airworthiness directive 
(AD), amendment 39-9866, to read as follows:

96-26-03  Fokker: Amendment 39-9866. Docket 96-NM-273-AD. Supersedes 
AD 96-24-10, amendment 39-9850.

    Applicability: All Model F28 Mark 0070 and 0100 series 
airplanes, certificated in any category.
    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (g) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.
    Compliance: Required as indicated, unless accomplished 
previously.
    To ensure protection against inadvertent deployment of the 
thrust reversers during flight, accomplish the following:
    (a) Within 48 hours after November 25, 1996 (the effective date 
of AD 96-23-16, amendment 39-9825), revise the Limitations Section 
of the FAA-approved Airplane Flight Manual (AFM) to include the 
following. This may be accomplished by inserting a copy of this AD 
in the AFM.
    ``Before take-off, arm the autothrottle system (ATS).
    When cleared for take-off, activate the take-off/go-around 
(TOGA) trigger(s), and positively verify ATS engagement [throttle 
movement and white steady AT1, AT2, or AT in the flight mode 
annunciator (FMA) engage window].
    If the ATS does NOT engage correctly, abort the take-off, 
return, and report to maintenance.
    If the ATS does engage correctly, you may continue take-off with 
either ATS engaged or disengaged, as necessary.
    (b) Within 48 hours after December 24, 1996 (the effective date 
AD 96-24-10, amendment 39-9850), revise the FAA-approved maintenance 
program to include the procedures specified in Appendix 2 of Fokker 
All Operator Message TS96.67591, dated November 14, 1996. These 
procedures must be accomplished daily, and prior to further flight 
following failure of the operational check required by paragraph (a) 
of this AD. If any failure is detected during these procedures, 
prior to further flight, accomplish the corrective actions in 
accordance with the procedures. The FAA-approved maintenance program 
procedures required by paragraph (a)(3) of AD 96-23-16, amendment 
39-9825, may be removed following accomplishment of the requirements 
of this paragraph.
    (c) Within 60 days after the effective date of this AD, modify 
the wiring of the electrical control, and indication and warning 
systems of the thrust reversers, in accordance with Fokker Service 
Bulletin SBF100-78-012, dated November 22, 1996. The AFM revision 
required by paragraph (a) of this AD and the FAA-approved 
maintenance program revision required by paragraph (b) of this AD 
may be removed following accomplishment of this paragraph.
    (d) For Model F28 Mark 0070 series airplanes: Prior to or in 
conjunction with the accomplishment of paragraph (c) of this AD, 
modify the wiring of the priority switching of the emergency 
inverter power supply in accordance with Fokker Service Bulletin 
SBF100-24-034, Revision 1, dated September 12, 1996.
    (e) Within 500 flight cycles following accomplishment of 
paragraph (c) of this AD, perform operational checks to detect 
failures of the secondary lock actuator, primary lock switch, 
indication and warning system, and feedback cable mechanism of the 
thrust reversers in accordance with Fokker Service Bulletin SBF100-
78-013, dated November 22, 1996. If any failure is detected, prior 
to further flight, repair the thrust reverser system in accordance 
with Chapter 78-30-00 of the Fokker Airplane Maintenance Manual. 
Repeat the operational checks thereafter at intervals not to exceed 
500 flight cycles.
    (f) Within 10 days after accomplishing the operational checks 
required by paragraphs (b) and (e) of this AD, submit a report of 
all findings to Fokker Services B.V., Technical Support Department, 
P.O. Box 75047, 1117 ZN Schiphol Airport, The Netherlands. 
Information collection requirements contained in this regulation 
have been approved by the Office of Management and Budget (OMB) 
under the provisions of the Paperwork Reduction Act of 1980 (44 
U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-
0056.
    (g) 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, Standardization Branch, ANM-113, 
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, 
Standardization Branch, ANM-113.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (h) 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.
    (i) The actions shall be done in accordance with Fokker All 
Operator Message TS96.67591, dated November 14, 1996; Fokker Service 
Bulletin SBF100-78-012, dated November 22, 1996; Fokker Service 
Bulletin SBF100-24-034, Revision 1, dated September 12, 1996; and 
Fokker Service Bulletin SBF100-78-013, dated November 22, 1996. 
Fokker Service Bulletin SBF100-24-034 contains the following list of 
effective pages:

------------------------------------------------------------------------
                                    Revision level                      
            Page No.                 shown on page    Date shown on page
------------------------------------------------------------------------
1-3.............................  1.................  September 12,     
                                                       1996.            
4-7.............................  Original..........  October 17, 1995. 
------------------------------------------------------------------------

    The incorporation by reference of Fokker All Operator Message 
TS96.67591, dated November 14, 1996, was approved previously by the 
Director of the Federal Register in

[[Page 607]]

accordance with 5 U.S.C. 552(a) and 1 CFR part 51. The incorporation 
by reference of the remainder of the service documents listed above 
is approved by the Director of the Federal Register in accordance 
with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from 
Fokker Service B.V., Technical Support Department, P.O. Box 75047, 
1117 ZN Schiphol Airport, The Netherlands. 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.
    (j) This amendment becomes effective on January 21, 1997.

    Issued in Renton, Washington, on December 20, 1996.

S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-161 Filed 1-3-97; 8:45 am]
BILLING CODE 4910-13-U