2010-19287. 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).

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: [phone].
• 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 [phone], extension 1; fax [phone]; e-mail [e-mail]; 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 [phone]) 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 [phone]; fax [phone].

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.

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 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.

§ 39.13

[Amended]

2. The FAA amends § 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 [phone]; fax [phone]. Or, e-mail information to [e-mail].

(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.