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[Federal Register: August 5, 2010 (Volume 75, Number 150)]
[Proposed Rules]               
[Page 47245-47247]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr05au10-24]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0706; Directorate Identifier 2010-NM-064-AD]
RIN 2120-AA64

 
Airworthiness Directives; The Boeing Company Model 747-400, 747-
400D, and 747-400F Series Airplanes Equipped With General Electric CF6-
80C2 or Pratt & Whitney PW4000 Series Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Model 747-400, 747-400D, and 747-400F series airplanes. This 
proposed AD would require modifying certain thrust reverser control 
system wiring to the flap control unit (FCU). This proposed AD results 
from a report of automatic retraction of the leading edge flaps due to 
indications transmitted to the FCU from the thrust reverser control 
system during takeoff. We are proposing this AD to prevent automatic 
retraction of the leading edge flaps during takeoff, which could result 
in reduced climb performance and consequent collision with terrain and 
obstacles or forced landing of the airplane.

DATES: We must receive comments on this proposed AD by September 20, 
2010.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-
544-5000, extension 1; fax 206-766-5680; e-mail me.boecom@boeing.com; 
Internet https://www.myboeingfleet.com. You may review copies of the 
referenced service information at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information 
on the availability of this material at the FAA, call 425-227-1221.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

FOR FURTHER INFORMATION CONTACT: Douglas Bryant, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6505; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2010-0706; 
Directorate Identifier 2010-NM-064-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.

[[Page 47246]]

    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    We received a report of automatic retraction of the leading edge 
(LE) flaps during takeoff on a Boeing Model 747-400 airplane equipped 
with Rolls-Royce Model RB211 series engines due to indications 
transmitted to the flap control unit (FCU) from the thrust reverser 
control system. The report indicated that the airplane had a REV amber 
indication on the number 3 engine thrust reverser, followed 13 seconds 
later by a REV amber indication on the number 2 engine. At the time of 
the second REV amber indication, the airplane was beyond V1 
(takeoff decision speed). In order to prevent impingement of efflux air 
from the thrust reversers, the FCU is designed to automatically retract 
the Group A LE flaps when a REV amber signal is transmitted from either 
both inboard or both outboard thrust reversers, and the airplane is on 
the ground. The FCU performed as designed and retracted the Group A LE 
flaps. At rotation the flightcrew reported buffeting and momentary 
stick shaker activation. After liftoff, a signal from the air/ground 
logic system caused the FCU to send a command to the Group A LE flaps 
to redeploy after a five-second time delay. Re-deployment of the flaps 
takes approximately ten to fifteen additional seconds. During re-
deployment, the flightcrew again reported buffeting and momentary stick 
shaker activation. The airplane jettisoned fuel and landed safely; all 
four of the thrust reversers deployed and stowed normally after 
landing.
    The automatic LE flap retraction logic for Model 747-400, -400D, 
and -400F series airplanes powered by General Electric (GE) Model CF6-
80C2 series engines and Pratt & Whitney (PW) Model PW4000 series 
engines automatically retracts the Group A LE flaps during reverse 
thrust operation. This is to prevent thrust reverser efflux air from 
impinging onto the Group A LE flaps, to improve the Group A LE flap 
panel's structural life. This function is armed when the airplane is on 
the ground. The Group A LE flaps retract when the FCU gets a signal 
from the LE flap relay in the reverser circuitry on the two inboard or 
the two outboard engines. The LE flap relay is energized by the 
microswitch of the reverse thrust lever, or the unstow microswitch in 
the center drive unit (GE Model CF6-80C2 series engines), or the unstow 
proximity sensor on the thrust reverser cowl (PW Model PW4000 series 
engines). The initial signal to the FCU comes from the microswitch in 
the aisle stand when thrust reverser deployment is commanded. For the 
CF6-80C2 series engines, the signal to the FCU is kept after stow is 
commanded by the center drive unit unstowed microswitches, and is 
removed once the thrust reverser is stowed. For the PW4000 series 
engines, the signal to the FCU is kept after stow is commanded by the 
proximity sensors, and is removed once the thrust reverser is stowed.
    These conditions, if not corrected, could result in reduced climb 
performance and consequent collision with terrain and obstacles or 
forced landing of the airplane.

Related AD

    The design for the thrust reverser signal to the FCU for the Rolls-
Royce Model RB211 series engines is the same as the GE Model CF6-80C2 
series engines and PW Model PW4000 series engines. Related AD 2009-13-
03, Amendment 39-15942 (74 FR 31169, June 30, 2009), applies to Boeing 
Model 747-400 and -400F series airplanes powered by Rolls-Royce RB211 
series engines, and addresses the same unsafe condition identified in 
this proposed AD. AD 2009-13-03 was issued as an Immediately Adopted 
Rule (IAR). The design of the thrust reverser uses a position sensor to 
indicate that the thrust reverser sleeve is unstowed (not fully 
stowed). This signal is used for the ``REV amber signal'' and also is 
used as an input to the flap control unit. Aerodynamic forces can cause 
the thrust reverser sleeve to flex which can be enough movement to 
cause the sensor to indicate that the sleeve is not fully stowed even 
though the sleeve has not moved from the stowed position.
    The reason for the IAR on the Rolls-Royce RB211 series engine 
installation was that the sensor is sensitive to small sleeve 
movements. There was also service experience of small sleeve movements 
that triggered a ``REV amber signal,'' similar to the incident 
airplane, but were only single engine occurrences. The sensors in the 
CF6-80C2 and PW4000 series engine installations are less sensitive to 
small sleeve movements. This is supported by service experience. In 
this case the risk is reduced and this allows for a less aggressive 
compliance time. This also allows us to proceed with issuing an NPRM to 
provide the public the opportunity to comment on the merits of the 
proposed requirements before the final rule is issued.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 747-78-
2183, dated January 12, 2010. This service bulletin describes 
procedures for modifying certain thrust reverser control system wiring 
to the FCU in the P414 and P415 power distribution panels for airplanes 
equipped with GE Model CF6-80C2 series engines. The modification 
includes re-routing and re-terminating one wire for each engine.
    We have also reviewed Boeing Alert Service Bulletin 747-78A2184, 
dated January 12, 2010. This service bulletin describes procedures for 
modifying certain thrust reverser control system wiring to the FCU in 
the P252 and P253 thrust reverser relay panels for airplanes equipped 
with PW Model PW4000 series engines. The modification includes re-
routing and re-terminating one wire for each engine.

FAA's Determination and Requirements of This Proposed AD

    We are proposing this AD because we evaluated all relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design. 
This proposed AD would require accomplishing the actions specified in 
the service information described previously.

Costs of Compliance

    We estimate that this proposed AD would affect 98 airplanes of U.S. 
registry. We also estimate that it would take about 1 work-hour per 
product to comply with this proposed AD. The average labor rate is $85 
per work-hour. Required parts would cost about $0 per product. Based on 
these figures, we estimate the cost of this proposed AD to the U.S. 
operators to be $8,330, or $85 per product.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. ``Subtitle VII: Aviation 
Programs,'' describes in more detail the scope of the Agency's 
authority.
    We are issuing this rulemaking under the authority described in 
``Subtitle VII, Part A, Subpart III, Section 44701: General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures

[[Page 47247]]

the Administrator finds necessary for safety in air commerce. This 
regulation is within the scope of that authority because it addresses 
an unsafe condition that is likely to exist or develop on products 
identified in this rulemaking action.

Regulatory Findings

    We determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect 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.
    For the reasons discussed above, I certify this proposed 
regulation:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866,
    2. Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979), and
    3. Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The FAA amends Sec.  39.13 by adding the following new AD:

The Boeing Company: Docket No. FAA-2010-0706; Directorate Identifier 
2010-NM-064-AD.

Comments Due Date

    (a) We must receive comments by September 20, 2010.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to The Boeing Company Model 747-400, 747-
400D, and 747-400F series airplanes; certificated in any category; 
equipped with General Electric CF6-80C2 series engines or Pratt & 
Whitney PW4000 series engines, as applicable.

Subject

    (d) Air Transport Association (ATA) of America Code 78: Engine 
exhaust.

Unsafe Condition

    (e) This AD results from a report of automatic retraction of the 
leading edge flaps during takeoff due to indications transmitted to 
the flap control unit (FCU) from the thrust reverser control system. 
The Federal Aviation Administration is issuing this AD to prevent 
automatic retraction of the leading edge flaps during takeoff, which 
could result in reduced climb performance and consequent collision 
with terrain and obstacles or forced landing of the airplane.

Compliance

    (f) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Modification

    (g) For Model 747-400 and -400F airplanes equipped with Pratt & 
Whitney Model PW4000 series engines: Within 36 months after the 
effective date of this AD, modify the thrust reverser control system 
wiring to the FCU in the P252 and P253 thrust reverser relay panels, 
in accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 747-78A2184, dated January 12, 2010.
    (h) For Model 747-400, -400D, and -400F airplanes equipped with 
General Electric Model CF6-80C2 series engines: Within 36 months 
after the effective date of this AD, modify the thrust reverser 
control system wiring to the FCU in the P414 and P415 power 
distribution panels, in accordance with Boeing Special Attention 
Service Bulletin 747-78-2183, dated January 12, 2010.

Alternative Methods of Compliance (AMOCs)

    (i)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. Send information to 
ATTN: Douglas Bryant, Aerospace Engineer, Propulsion Branch, ANM-
140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue 
SW., Renton, Washington 98057-3356; telephone (425) 917-6505; fax 
(425) 917-6590. Or, e-mail information to 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your principal maintenance inspector (PMI) or 
principal avionics inspector (PAI), as appropriate, or lacking a 
principal inspector, your local Flight Standards District Office. 
The AMOC approval letter must specifically reference this AD.

    Issued in Renton, Washington on July 26, 2010.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2010-19287 Filed 8-4-10; 8:45 am]
BILLING CODE 4910-13-P
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