2013-29310. Airworthiness Directives; The Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.

SUMMARY:

We are revising an earlier supplemental notice of proposed rulemaking (SNPRM) for all The Boeing Company Model 737-600, -700, -700C, -800, -900 and -900ER series airplanes. The SNPRM proposed to require inspecting for a serial number that starts with the letters “SAIC” on the left- and right-side horizontal stabilizer identification plate; inspecting for correct bolt protrusion and chamfer of the termination fitting bolts of the horizontal stabilizer rear spar, if necessary; inspecting to determine if certain bolts are installed, if necessary; and doing related investigative and corrective actions if necessary. The SNPRM was prompted by reports of incorrectly installed bolts common to the rear spar termination fitting on the horizontal stabilizer. This action revises the SNPRM by revising the applicable thresholds from flight cycles on the airplane to flight cycles accumulated on the affected horizontal stabilizer. We are proposing this SNPRM to prevent loss of structural integrity of the horizontal stabilizer attachment and loss of control of the airplane. Since these actions impose an additional burden over that proposed in the earlier SNPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.

DATES:

We must receive comments on this SNPRM by January 23, 2014.

ADDRESSES:

You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, 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]; Internet https://www.myboeingfleet.com. You may view this referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. 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:

Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, 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 proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2012-0268; Directorate Identifier 2011-NM-129-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 issued a supplemental notice of proposed rulemaking (SNPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. The SNPRM published in the Federal Register on March 7, 2013 (78 FR 14734). The notice of proposed rulemaking (NPRM) published in the Federal Register on March 20, 2012 (77 FR 16188). The SNPRM added airplanes to the applicability of the NPRM, which proposed to require inspecting for a serial number that starts with the letters “SAIC” on the left- and right-side horizontal stabilizer identification plate; inspecting for correct bolt protrusion and chamfer of the termination fitting bolts of the horizontal stabilizer rear spar, if necessary; inspecting to determine if certain bolts are installed, if necessary; and doing related investigative and corrective actions if necessary.

Actions Since First SNPRM Was Issued

Since we issued the first SNPRM (78 FR 14734, March 7, 2013), we have determined that the applicable thresholds need to be revised from flight cycles on the airplane to flight cycles accumulated on the affected horizontal stabilizer.

Comments

We gave the public the opportunity to comment on the first SNPRM (78 FR 14734, March 7, 2013). The following presents the comments received on the first SNPRM and the FAA's response to each comment.

Request To Revise Applicability

Boeing requested that the applicability of the first SNPRM (78 FR 14734, March 7, 2013) be revised to apply only to the airplanes specified in Boeing Service Bulletin 737-55-1090, dated March 30, 2011, and that the FAA establish operator responsibility in lieu of revising the applicability to include all line numbers. Boeing stated that it is the operators' responsibility to maintain records, including flight cycles on principal structural elements, and that the horizontal stabilizer is not designed as a rotable part and no interchangeability notes are included on drawings.

We disagree. In the comments to the NPRM (77 FR 16188, dated March 20, 2012), one operator commented that stabilizers are rotated among airplanes. Therefore, the applicability of the NPRM was incorrect. The first SNPRM (78 FR 14734, March 7, 2013) was issued to open the applicability to “all” affected airplane models to address the possibility that stabilizers have been (or can be) rotated among the fleet. Even if an operator knows the stabilizer has been rotated to another airplane, if that airplane is not included in the applicability of this proposed second SNPRM, there would be no requirement to inspect that stabilizer; hence, this SNPRM should apply to all The Boeing Company Model 737-600, -700, -700C, -800, -900 and -900ER series airplanes. Although the Boeing comment stated that the stabilizers are not designed to be a rotable part, we note that Boeing Document D042A525, “Compliance Document and Repair Evaluation Guidelines, Damage Tolerance Data for Repairs and Alterations − 14CFR 26 Subpart F,” applicable to the 737-600/700/700C/800/900/900ER fleet, does include the horizontal stabilizer in the listing of Replaceable Structural Components requiring consideration for compliance with section 121.1109(c)(2) or section 129.109(b)(2) of the Federal Aviation Regulations (14 CFR 121 or 14 CFR 129), as applicable. We have not changed this second SNPRM in this regard.

Request To Revise Compliance Time

Boeing requested that the FAA establish operator responsibility by adding the following note to the AD:

Initial inspection (threshold) and intervals are measured in flight cycles or flight hours that a particular principle structural element (PSE) detail has accumulated regardless of what the airframe as a whole has accumulated. Most PSE details have never been replaced and therefore have accumulated the same flight cycles and flight hours as the airframe. Some PSE details are replaced, such as when installing Removable Structural Components (repairable/rotable/expendables) or installing used structural parts as a repair. In these cases the PSE details have accumulated flight cycles and flight hours that may be different than the airframe. The operator must account for this in determining when inspections must be done. In determining the PSE flight cycles or flight hours, operators may use the process defined in Advisory Circular 120-93.

Boeing also proposed to add the note to Boeing Service Bulletin 737-55-1090, dated March 30, 2011. Boeing stated that the note is in use in the 737 Maintenance Planning Data (MPD) Section 9, Airworthiness Limitations D926A001-CMR, as well as the MPD Airworthiness Limitations sections of other Boeing models, to address FAA concerns about operators interchanging parts during maintenance that Boeing had never intended to be rotable.

We partially agree. We agree with clarifying the compliance time for the requirements of paragraphs (g) and (h) of this second SNPRM by specifying total flight cycles accumulated on the horizontal stabilizer. Inspection thresholds measured in “total flight cycles” must be the number of total flight cycles accumulated on the principal structural element, which may differ from airframe cycles if the horizontal stabilizer has been rotated to a different airplane. We have added paragraph (i) to this second SNPRM to clarify that the compliance times for paragraphs (g) and (h) of this second SNPRM are total flight cycles accumulated on the horizontal stabilizer since new, and we have moved the information contained in paragraph (i) of the first SNPRM to paragraph (j)(1) of this second SNPRM. We disagree that it is necessary to add this note to this second SNPRM.

Request To Clarify Applicability

All Nippon Airways (ANA) requested that paragraphs (g) and (h) of the first SNPRM (78 FR 14734, March 7, 2013) be clarified to specify which airplanes are subject to the requirements, since the applicability of the SNPRM includes airplanes after line number (L/N) 1556, which are not addressed by Boeing Service Bulletin 737-55-1090, dated March 30, 2011.

We agree. We have revised paragraphs (g) and (h) of this second SNPRM to specify that Group 1 airplanes are Model 737-600, -700, -800, -900 and -900ER airplanes, regardless of line number, and that Group 2 airplanes are Model 737-700C airplanes, regardless of line number. We have also added paragraphs (j)(4) and (j)(5) to this second SNPRM to clarify that, where the service information specifies Group 1 airplanes as Model 737-600, -700, -800, and -900 airplanes having line numbers 379 through 1556 inclusive, this AD specifies Group 1 airplanes as all Model 737-600, -700, -800, -900, and -900ER airplanes, regardless of line number, and where the service information specifies Group 2 airplanes as Model 737-700C airplanes having line numbers 496 through 1548 inclusive, this AD specifies Group 2 airplanes as all Model 737-700C airplanes, regardless of line number.

Request To Allow Records Check To Identify Suspect Horizontal Stabilizers

All Nippon Airways (ANA) requested that we revise paragraph (g) of the first SNPRM (78 FR 14734, March 7, 2013) to allow a records check of the maintenance records and delivery documentation to confirm that the horizontal stabilizer has not been rotated from the airplane. ANA stated that, with this revision, the requirements of paragraph (g) would not apply to airplanes after L/N 1556, even if the horizontal stabilizer has a serial number beginning with “SAIC,” because the discrepant stabilizers were delivered on airplanes prior to L/N 1557.

We agree. By comparing the horizontal stabilizer serial number with the serial number shown on the delivery documentation for that airplane, an operator can confirm that the horizontal stabilizer is not subject to the unsafe condition. We have revised paragraphs (g) and (h) in this second SNPRM by adding a provision specifying that a review of manufacturer delivery and operator maintenance records is acceptable to make the determination, if the horizontal stabilizer serial number can be conclusively identified from that review. We also added paragraph (g)(2) in this second SNPRM to state that if a serial number starting with the letters “SAIC” is found on a horizontal stabilizer identification plate on airplanes after L/N 1556, and the serial number of the horizontal stabilizer on the airplane is the same as the serial number in the delivery documentation, no further action is required by this SNPRM for that horizontal stabilizer.

Request To Provide Serial Numbers of Discrepant Horizontal Stabilizers

TUIfly Fluggesellschaft mbH requested that we revise paragraph (g) of the first SNPRM (78 FR 14734, March 7, 2013) to provide complete serial numbers for the discrepant horizontal stabilizers identified in the AD, instead of using only the first letters, “SAIC,” since those horizontal stabilizers having a serial number beginning with “SAIC,” which were not originally installed in airplanes after L/N 1556, are not considered to be suspect and should not require the inspection.

We disagree with the request. Although identifying the serial numbers of all suspect parts would be useful to eliminate the need to inspect all horizontal stabilizers, we do not have this information. If the serial numbers are provided to us or to the operators, under the provisions of paragraph (l) of this second SNPRM, we may approve requests to exclude non-suspect horizontal stabilizers from the requirements of paragraphs (g) and (h) of this second SNPRM. We have not changed this second SNPRM in this regard.

Request To Clarify Parts Installation Limitation

ANA requested that the parts installation limitation specified in paragraph (k) of the first SNPRM (78 FR 14734, March 7, 2013) be clarified to exclude horizontal stabilizers that have a serial number beginning with “SAIC” and that were delivered on airplanes after L/N 1556.

We disagree with revising the wording in paragraph (k) of this second SNPRM, because each horizontal stabilizer rotated after the effective date of this second SNPRM must be confirmed to be suspect or non-suspect as the stabilizer may have been previously rotated from another airplane having a line number before L/N 1557. If the stabilizer is found to be suspect, then the inspections required in paragraphs (g) and (h) of this second SNPRM must be accomplished. We have not changed this second SNPRM in this regard.

FAA's Determination

We are proposing this second SNPRM 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. Certain changes described above expand the scope of the SNPRM (78 FR 14734, March 7, 2013). As a result, we have determined that it is necessary to reopen the comment period to provide additional opportunity for the public to comment on this second SNPRM.

Proposed Requirements of This Second SNPRM

This second SNPRM would require inspecting for a serial number that starts with the letters “SAIC” on the left- and right-side horizontal stabilizer identification plate; inspecting for correct bolt protrusion and chamfer of the termination fitting bolts of the horizontal stabilizer rear spar, if necessary; inspecting to determine if certain bolts are installed, if necessary; and doing related investigative and corrective actions if necessary.

Clarification of Compliance Time

While it can be inferred that the compliance times stated in Boeing Service Bulletin 737-55-1090, dated March 30, 2011, are total flight cycles on the airplane since new, this second SNPRM specifies compliance times as total flight cycles accumulated on the horizontal stabilizer since new. Also, for repetitive inspection intervals, where the service information specifies “flight cycles,” this second SNPRM clarifies “flight cycles accumulated on the horizontal stabilizer.”

Explanation of Change Made to This Second SNPRM

We clarified the wording in paragraph (g)(2) of this second SNPRM to specify that if the serial number found on a horizontal stabilizer identification plate matches the serial number of the horizontal stabilizer stated in the delivery documentation of the airplane, no further action is required by paragraph (g) of this second SNPRM.

Costs of Compliance

We estimate that this proposed AD affects 1,147 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	1 work-hour × $85 per hour = $85 per inspection cycle	$0	$85	$97,495
Replacement of bolts	17 work-hours × $85 per hour = $1,445	1,530	2,975	3,412,325

We have received no definitive data that would enable us to provide a cost estimate for the on-condition actions (contacting Boeing and repairing cracks or damage) specified in this proposed AD.

According to the manufacturer, some of the costs of this proposed AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all costs in our cost estimate.

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-2012-0268; Directorate Identifier 2011-NM-129-AD.

(a) Comments Due Date

We must receive comments by January 23, 2014.

(b) Affected ADs

None.

(c) Applicability

(1) This AD applies to all The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes, certificated in any category.

(2) Installation of Supplemental Type Certificate (STC) ST00830SE (http://rgl.faa.gov/​Regulatory_​and_​Guidance_​Library/​rgstc.nsf/​0/​408E012E008616A7862578880060456C?​OpenDocument&​Highlight=​st00830se) does not affect the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST00830SE is installed, a “change in product” alternative method of compliance (AMOC) approval request is not necessary to comply with the requirements of 14 CFR 39.17.

(d) Subject

Air Transport Association (ATA) of America Code 55, Stabilizers.

(e) Unsafe Condition

This AD was prompted by reports of incorrectly installed bolts common to the rear spar termination fitting of the horizontal stabilizer. We are issuing this AD to prevent loss of structural integrity of the horizontal stabilizer attachment and loss of control of the airplane.

(f) Compliance

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

(g) Inspecting the Horizontal Stabilizer and Corrective Actions

For Group 1 and Group 2 airplanes identified in Boeing Service Bulletin 737-55-1090, dated March 30, 2011, except as provided by paragraph (j) of this AD: At the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Service Bulletin 737-55-1090, dated March 30, 2011, except as provided by paragraph (i) of this AD, do an inspection for a serial number that starts with the letters “SAIC” on the identification plates of the left- and right-side horizontal stabilizers, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-55-1090, dated March 30, 2011. A review of manufacturer delivery and operator maintenance records is acceptable to make the determination specified in this paragraph if the serial number can be conclusively identified from that review.

(1) If no “SAIC” serial number is found, no further action is required by paragraph (g) of this AD.

(2) If a serial number starting with the letters “SAIC” is found on a horizontal stabilizer identification plate on an airplane after line number (L/N) 1556, and the serial number of the horizontal stabilizer is the same as stated in the delivery documentation of the airplane, no further action is required by paragraph (g) of this AD for that horizontal stabilizer.

(3) If a serial number starting with the letters “SAIC” is found on a horizontal stabilizer identification plate, except as specified in paragraph (g)(2) of this AD: Except as provided by paragraphs (i) and (j) of this AD, at the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Service Bulletin 737-55-1090, dated March 30, 2011, do a detailed inspection for correct bolt protrusion and correct chamfer of the termination fitting bolts of the horizontal stabilizer rear spar, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-55-1090, dated March 30, 2011. Concurrently with the detailed inspection, inspect to determine if any bolt other than part number (P/N) BACB30US14K() or BACB30US16K(), as applicable, is installed. Before further flight, do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-55-1090, dated March 30, 2011.

(h) High Frequency Eddy Current (HFEC) and Ultrasonic Inspections of Termination Fitting and Repair

For airplanes identified in paragraph (g)(3) of this AD at any location where a new bolt having a P/N BACB30US14K() is installed as corrective action for damage found during any inspection required by paragraph (g) of this AD: Except as provided by paragraphs (i) and (j)(1) of this AD, at the times specified in paragraph 1.E., “Compliance,” of Boeing Service Bulletin 737-55-1090, dated March 30, 2011, do HFEC and ultrasonic inspections for cracking of the forward and aft sides of the termination fitting, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-55-1090, dated March 30, 2011. If any crack is found in any termination fitting: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (l) of this AD. Repeat the HFEC and ultrasonic inspections thereafter at intervals not to exceed 3,500 flight cycles on the horizontal stabilizer.

(i) Clarification of Compliance Time

Where the compliance times stated in Boeing Service Bulletin 737-55-1090, dated March 30, 2011, are “total flight cycles,” the compliance time in this AD is total flight cycles accumulated on the horizontal stabilizer since new.

(j) Exceptions to Service Information Specifications

(1) Where Boeing Service Bulletin 737-55-1090, dated March 30, 2011, specifies a compliance time “after the original issue date on the service bulletin,” this AD requires compliance within the specified compliance time after the effective date of this AD.

(2) Where Figure 1 of Boeing Service Bulletin 737-55-1090, dated March 30, 2011, points to the location of a part number rather than the serial number, this AD requires an inspection for an identification plate with a serial number that starts with the letters “SAIC.”

(3) If, during any inspection required by paragraphs (g) and (h) of this AD, any bolt other than P/N BACB30US14K() or BACB30US16K(), as applicable, is found: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (l) of this AD.

(4) Where Boeing Service Bulletin 737-55-1090, dated March 30, 2011, identifies Group 1 airplanes as 737-600, -700, -800, and -900 airplanes having line numbers 379 through 1556 inclusive, this AD specifies Group 1 airplanes as all 737-600, -700, -800, -900, and -900ER airplanes, regardless of line number.

(5) Where Boeing Service Bulletin 737-55-1090, dated March 30, 2011, identifies Group 2 airplanes as 737-700C airplanes having line number 496 through 1548 inclusive, this AD specifies Group 2 airplanes as all 737-700C airplanes, regardless of line number.

(k) Parts Installation Limitation

As of the effective date of this AD, no person may install a horizontal stabilizer on any airplane included in the applicability of this AD, unless the horizontal stabilizer has been inspected and any applicable corrective actions done in accordance with paragraphs (g) and (h) of this AD.

(l) Alternative Methods of Compliance (AMOCs)

(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 paragraph (m) 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 the 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.

(m) Related Information

(1) For more information about this AD, contact Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, 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]; 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 December 2, 2013.

John P. Piccola,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.