2012-11019. Airworthiness Directives; The Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-600, -700, -800, -900, and -900ER series airplanes. This proposed AD was prompted by reports that certain seat track bolts were found with severed head bolts due to fatigue. This proposed AD would require replacing titanium seat track bolts with corrosion resistant steel (CRES) bolts, repetitive inspections for cracking of the splice strap and forward seat track holes, and related investigative and corrective actions if necessary. This proposed AD also provides an optional terminating action for the repetitive inspections. We are proposing this AD to detect and correct missing or severed bolt heads, which, if not corrected, could result in the inability of the seat track to carry passenger loads, which could cause the seats to detach from the seat track, resulting in possible injury to passengers during an emergency landing.

DATES:

We must receive comments on this proposed AD by June 22, 2012.

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, Washington 98124-2207; telephone [phone], extension 1; fax [phone]; email [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:

Patrick Gillespie, Aerospace Engineer, Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: [phone]; fax: [phone]; email: [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-2012-0426; Directorate Identifier 2011-NM-087-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 reports indicating that the seat track bolts at Station 727B, buttock lines (BL) 24.75 and 45.50 left and right sides, were found with severed bolt heads due to fatigue. Missing or severed bolt heads, if not detected and corrected, could result in the inability of the seat track to carry passenger loads, which could cause the seats to detach from the seat track, resulting in possible injury to passengers during an emergency landing.

Relevant Service Information

We reviewed Boeing Special Attention Service Bulletin 737-53-1296, dated January 11, 2011. That service information describes procedures for replacing titanium seat track bolts with CRES bolts, repetitive inspections for cracking of the splice strap and forward seat track holes, and related investigative and corrective actions if necessary.

Related investigative action includes detailed inspection and high frequency eddy current (HFEC) inspections for cracking in holes common to the splice strap and forward seat track.

Corrective actions include contacting Boeing for repair instructions, repairing, replacing missing or severed titanium seat track bolts with CRES bolts, and replacing a cracked splice strap with a new slice strap. Replacing the missing or severed seat track bolts and installing the new splice strap eliminates the need for the repetitive splice strap inspections at Station 727B, BL 24.75 and 45.50, left and right sides, on all airplanes.

For the inspections for cracking of the splice strap and forward seat track holes and replacement of missing or severed seat track bolts, the service information specifies an initial compliance time of before 7,000 total flight cycles or within 24 months after the issue date of the service bulletin, and a repetitive interval of 7,000 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, except as discussed below.

Differences Between Proposed AD and Service Bulletin

Although Boeing Special Attention Service Bulletin 737-53-1296, dated January 11, 2011, specifies that operators may contact the manufacturer for disposition of certain repair conditions, this proposed AD would require operators to repair those conditions using a method approved by the FAA.

Although Boeing Special Attention Service Bulletin 737-53-1296, dated January 11, 2011, specifies the sequence of steps performed in that service bulletin can be changed, this proposed AD would require operators to perform the repair using the sequence of steps in that service bulletin.

Costs of Compliance

We estimate that this proposed AD affects 168 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
Replace bolts and install new splice strap	18 work-hours × $85 per hour = $1,530	$1,991	$3,521	$591,528
Repetitive Inspection	3 work-hours × $85 per hour = $255	0	255	42,840

We have received no definitive data that would enable us to provide cost estimates for the on-condition actions specified in this proposed AD.

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-2012-0426; Directorate Identifier 2011-NM-087-AD.

(a) Comments Due Date

We must receive comments by June 22, 2012.

(b) Affected ADs

None.

(c) Applicability

This AD applies to The Boeing Company Model 737-600, -700, -800, -900, and -900ER series airplanes, with passenger seats installed; certificated in any category; as identified in Boeing Special Attention Service Bulletin 737-53-1296, dated January 11, 2011.

(d) Subject

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

(e) Unsafe Condition

This AD was prompted by reports that certain seat track bolts were found with severed bolt heads due to fatigue. We are issuing this AD to detect and correct missing or severed bolt heads, which, if not corrected, could result in the inability of the seat track to carry passenger loads, which could cause the seats to detach from the seat track, resulting in possible injury to passengers during an emergency landing.

(f) Compliance

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

(g) Seat Track Bolt Replacement and Splice Strap Installation

Before the accumulation of 7,000 total flight cycles, or within 24 months after the effective date of this AD, whichever occurs later, replace titanium seat track bolts with corrosion resistant steel (CRES) bolts at both the left and right sides of buttock lines 24.75 and 45.50, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-53-1296, dated January 11, 2011. If a titanium seat track bolt is found missing from the structure during the accomplishment of the tasks required by this paragraph: Before further flight, do a high frequency eddy current (HFEC) inspection for cracking in the fastener holes and do a general visual inspection of the area, including the splice strap and forward seat track for damage, and replace missing bolts with new or serviceable CRES bolts, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-53-1296, dated January 11, 2011. If cracking or damage is found: Before further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

(h) Detailed and High Frequency Eddy Current Inspections

Before the accumulation of 7,000 total flight cycles, or within 24 months after the effective date of this AD, whichever occurs later: Do a detailed inspection and an HFEC inspection for cracking in the holes common to the splice strap and forward seat track at both the left and right sides of buttock lines 24.75 and 45.50, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-53-1296, dated January 11, 2011. Repeat the inspections thereafter at intervals not to exceed 7,000 flight cycles, until the actions specified in paragraph (i) of this AD have been done.

(1) If a crack is found in the splice strap during any inspection required by paragraph (h) of this AD: Before further flight, replace the seat track bolts and install a new splice strap part number (P/N) 146A5342-26 and retained angle at the affected location, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-53-1296, dated January 11, 2011.

(2) If a crack is found in the seat track during any inspection required by paragraph (h) of this AD, and Boeing Special Attention Service Bulletin 737-53-1296, dated January 11, 2011, specifies to contact Boeing for appropriate action: Before further flight, repair the seat track in accordance with a method approved by the Manager, Seattle ACO, FAA. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

(i) Optional Terminating Action

Replacing the titanium seat track bolts with CRES bolts on both the left and right sides of buttock lines 24.75 and 45.50 at Station 727B, and installing a new splice strap P/N 146A5342-26, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-53-1296, dated January 11, 2011, terminates the repetitive inspections required by paragraph (h) of this AD.

(j) Alternative Methods of Compliance (AMOCs)

(1) The Manager, Seattle 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 emailed 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 Boeing Commercial Airplanes Organization Designation Authorization (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, and the approval must specifically refer to this AD.

(k) Related Information

(1) For more information about this AD, contact Patrick Gillespie, Aerospace Engineer, Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: [phone]; fax: [phone]; email: [e-mail].

(2) For service information identified in this 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]; email [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 April 29, 2012.

Michael Kaszycki,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.