2011-22371. Airworthiness Directives; The Boeing Company Model 747 Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD would require repetitive general visual inspections for broken or missing latch pins of the lower sills of the forward and aft lower lobe cargo doors; repetitive detailed inspections for cracking of the latch pins; and corrective actions if necessary. This proposed AD was prompted by reports of fractured latch pins found in service; investigation revealed that the cracking and subsequent fracture were initiated by fatigue and propagated by a combination of fatigue and stress corrosion. We are proposing this AD to detect and correct fractured or broken latch pins, which could result in a forward or aft lower lobe cargo door opening and detaching during flight, and consequent rapid decompression of the airplane.

DATES:

We must receive comments on this proposed AD by October 17, 2011.

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: Deliver to Mail address above 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, WA 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 (phone: [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Nathan Weigand, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; phone: [phone]; fax: [phone]; e-mail: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2011-0915; Directorate Identifier 2011-NM-020-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 have received reports of fractured latch pins found in service; investigation revealed that the cracking and subsequent fracture were initiated by fatigue and propagated by a combination of fatigue and stress corrosion. One operator reported a fractured latch pin of the lower sill of the aft lower lobe cargo door; the fracture initiated from a crack on the pin's internal diameter. Part of the pin was found on the ground during an airplane walk-around. The airplane had accumulated 75,495 total flight hours and 9,393 total flight cycles. A dye penetrant inspection of the remaining seven latch pins in the lower sill was done with no defects found. This condition, if not corrected, could result in a forward or aft lower lobe cargo door opening and detaching during flight, and consequent rapid decompression of the airplane.

Relevant Service Information

We reviewed Boeing Alert Service Bulletin 747-53A2835, original, dated October 28, 2010. The service information describes procedures for repetitive general visual inspections for broken or missing latch pins of the lower sills of the forward and aft lower lobe cargo doors; repetitive detailed inspections of the replaced latch pins for broken or missing latch pins; and corrective actions if necessary.

For Groups 1 and 2 airplanes, Configurations 1 and 2; and for Group 3 airplanes; the corrective actions include replacing any broken or missing latch pin, and the latch pins at the adjacent latch fitting locations, with new latch pins; and replacing any cracked latch pins with new latch pins.

For Group 1 airplanes, Configurations 3 and 4, there are two options for corrective actions:

• Replacing any broken or missing latch pin, and the latch pins at the adjacent latch fitting locations, with new latch pins (with identical part numbers); and replacing any cracked latch pins with new latch pins (with identical part numbers).
• Modifying or replacing the latch pins and bearing plates; replacing any broken or missing latch pin, and the latch pins at the adjacent latch fitting locations, with new latch pins (with alternative part numbers); and replacing any cracked latch pins with new latch pins (with alternative part numbers).

For airplanes on which all latch pins are replaced, the first repetitive inspection interval is within 6,000 flight cycles after replacement. For airplanes on which not all of the latch pins are replaced, the first repetitive inspection interval is 1,600 flight cycles after inspecting. For all airplanes, the repetitive interval for subsequent inspections is 1,600 flight cycles.

FAA's Determination

We are proposing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of these same type designs.

Proposed AD Requirements

This proposed AD would require accomplishing the actions specified in the service information described previously.

Interim Action

We consider this proposed AD interim action. The manufacturer is currently developing a modification that will address the unsafe condition identified in this AD. Once this modification is developed, approved, and available, we might consider additional rulemaking.

Costs of Compliance

We estimate that this proposed AD affects 228 airplanes of U.S. registry.

We estimate the following costs to comply with this proposed AD:

Estimated Costs

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Inspection	3 work-hours × $85 per hour = $255 per inspection cycle	$0	$255 per inspection cycle	$58,140 per inspection cycle.

We estimate the following costs to do any necessary replacements/modifications that would be required based on the results of the proposed inspection. We have no way of determining the number of aircraft that might need these actions:

On-Condition Costs

Action	Labor cost	Parts cost	Cost per product
Replacement of latch pins	8 work-hours × $85 per hour = $680	$0	$680
Modification of latch fittings	36 hours × $85 per work-hours = $3,060	0	3,060

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),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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.

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 airworthiness directive (AD):

The Boeing Company: Docket No. FAA-2011-0915; Directorate Identifier 2011-NM-020-AD.

Comments Due Date

(a) We must receive comments by October 17, 2011.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes; certificated in any category.

Subject

(d) Joint Aircraft System Component (JASC)/Air Transport Association (ATA) of America Code 53: Fuselage.

Unsafe Condition

(e) This AD was prompted by reports of fractured latch pins found in service; investigation revealed that the cracking and subsequent fracture were initiated by fatigue and propagated by a combination of fatigue and stress corrosion. We are issuing this AD to detect and correct fractured or broken latch pins, which could result in a forward or aft lower lobe cargo door opening and detaching during flight, and consequent rapid decompression of the airplane.

Compliance

(f) Comply with this AD within the compliance times specified, unless already done.

Inspections

(g) Before the accumulation of 6,000 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later: Do a general visual inspection for broken or missing latch pins of the lower sills of the forward and aft lower lobe cargo doors, and a detailed inspection for cracking of the latch pins, in accordance with paragraph 3.B., “Work Instructions,” of Boeing Alert Service Bulletin 747-53A2835, original, dated October 28, 2010. Repeat the inspections thereafter at the applicable intervals specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2835, original, dated October 28, 2010. Before further flight, do all applicable corrective actions, in accordance with paragraph 3.B., “Work Instructions,” of Boeing Alert Service Bulletin 747-53A2835, original, dated October 28, 2010.

Special Flight Permits

(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 airplane can be modified (if the operator elects to do so), provided the cabin is not pressurized.

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. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ACO, send it to the attention of the person identified in the Related Information section of this AD. Information may be e-mailed to: [e-mail].

(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.

(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD if it is approved by the Boeing Commercial Airplanes ODA that has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane.

Related Information

(j) For more information about this AD, contact Nathan Weigand, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; phone: [phone]; fax: [phone]; e-mail: [e-mail].

(k) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, WA 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.

Issued in Renton, Washington, on August 25, 2011.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.