Document Headings

                    Document headings vary by document type but may contain                    the following:                  
                -                       the agency or agencies that issued and signed a document                    
                -                       the number of the CFR title and the number of each part                      the document amends, proposes to amend, or is directly                      related to                    
                -                       the agency docket number / agency internal file number                    
                -                       the RIN which identifies each regulatory action listed in                      the Unified Agenda of Federal Regulatory and Deregulatory                      Actions                    

                    See the                                          Document Drafting Handbook                                        for more details.                  

###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [Docket No. FAA-2021-0099; Project Identifier AD-2020-01272-T]
          - RIN 2120-AA64

# AGENCY:

Federal Aviation Administration (FAA), DOT.

# ACTION:

Notice of proposed rulemaking (NPRM).

# SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 767-200, -300, -300F, and -400ER series airplanes. This proposed AD was prompted by significant changes made to the airworthiness limitations (AWLs) related to fuel tank ignition prevention and the nitrogen generation system. This proposed AD would require revising the existing maintenance or inspection program, as applicable, to incorporate the latest revision of the AWLs. The FAA is proposing this AD to address the unsafe condition on these products.

# DATES:

The FAA must receive comments on this proposed AD by April 12, 2021.

# 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                          https://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:                          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 NPRM, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; telephone 562-797-1717; internet                         *https://www.myboeingfleet.com.*                         You may view this service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195.                    

## Examining the AD Docket

                    You may examine the AD docket on the internet at                     *https://www.regulations.gov*                     by searching for and locating Docket No. FAA-2021-0099; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this NPRM, any comments received, and other information. The street address for Docket Operations is listed above.                

# FOR FURTHER INFORMATION CONTACT:

                        Rebel Nichols, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3556; email:                         *rebel.nichols@faa.gov.*

# SUPPLEMENTARY INFORMATION:

## Comments Invited

                    The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under                     **ADDRESSES**                    . Include “Docket No. FAA-2021-0099; Project Identifier AD-2020-01272-T” at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may amend the proposal because of those comments.                

                    Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR                           ( print page 11654)                        11.35, the FAA will post all comments received, without change, to                     *https://www.regulations.gov,*                     including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this proposed AD.                

## Confidential Business Information

                    CBI is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to this NPRM contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as “PROPIN.” The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI should be sent to Rebel Nichols, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3556; email:                     *rebel.nichols@faa.gov.*                     Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.                

## Background

The FAA has examined the underlying safety issues involved in fuel tank explosions on several large transport airplanes, including the adequacy of existing regulations, the service history of airplanes subject to those regulations, and existing maintenance practices for fuel tank systems. As a result of those findings, the FAA issued a final rule titled “Transport Airplane Fuel Tank System Design Review, Flammability Reduction and Maintenance and Inspection Requirements” (66 FR 23086, May 7, 2001). In addition to new airworthiness standards for transport airplanes and new maintenance requirements that rule included Amendment 21-78, which established Special Federal Aviation Regulation No. 88 (SFAR 88) at 14 CFR part 21. Subsequently, SFAR 88 was amended by Amendment 21-82 (67 FR 57490, September 10, 2002; corrected at 67 FR 70809, November 26, 2002), Amendment 21-83 (67 FR 72830, December 9, 2002; corrected at 68 FR 37735, June 25, 2003, to change “21-82” to “21-83”), and Amendment 21-101 (83 FR 9162, March 5, 2018).

                    Among other actions, SFAR 88 requires certain type design (                    *i.e.,*                     type certificate (TC) and supplemental type certificate (STC)) holders to substantiate that their fuel tank systems can prevent ignition sources in the fuel tanks. This requirement applies to type design holders for large turbine-powered transport airplanes and for subsequent modifications to those airplanes. It requires them to perform design reviews and to develop design changes and maintenance procedures if their designs do not meet the new fuel tank safety standards. As explained in the preamble to the final rule published on May 7, 2001, the FAA intended to adopt airworthiness directives to mandate any changes found necessary to address unsafe conditions identified as a result of these reviews.                

In evaluating these design reviews, the FAA has established four criteria intended to define the unsafe conditions associated with fuel tank systems that require corrective actions. The percentage of operating time during which fuel tanks are exposed to flammable conditions is one of these criteria. The other three criteria address the failure types under evaluation: Single failures, single failures in combination with another latent condition(s), and in-service failure experience. For all four criteria, the evaluations included consideration of previous actions taken that may mitigate the need for further action.

This proposed AD was prompted by significant changes made to the AWL related to fuel tank ignition prevention and the nitrogen generation system. This condition, if not addressed, could result in the potential for ignition sources inside fuel tanks caused by latent failures, alterations, repairs, or maintenance actions, which, in combination with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of the airplane.

The FAA has determined that accomplishing the revision required by paragraph (g) of this proposed AD would terminate the following requirements for that airplane:
    - The revision required by paragraphs (g) and (h) of AD 2008-11-01 R1, Amendment 39-16145 ( 74 FR 68515 , December 28, 2009).
    - The revision required by paragraph (h) of AD 2010-06-10, Amendment 39-16234 ( 75 FR 15322 , March 29, 2010) (AD 2010-06-10).
    - The revision required by paragraph (k) of AD 2011-25-05, Amendment 39-16881 ( 77 FR 2442 , January 18, 2012) (AD 2011-25-05).
    - The revision required by paragraph (n) of AD 2013-25-02, Amendment 39-17698 ( 79 FR 24541 , May 1, 2014) (AD 2013-25-02).
    - The revision required by paragraph (g) of AD 2014-08-09, Amendment 39-17833 ( 79 FR 24546 , May 1, 2014) (AD 2014-08-09).
    - The revision required by paragraph (h) of AD 2014-20-02, Amendment 39-17975 ( 79 FR 59102 , October 1, 2014) (AD 2014-20-02).
    - The revision required by paragraphs (i)(3)(i) and (ii) of AD 2018-20-13, Amendment 39-19447 ( 83 FR 52305 , October 17, 2018) (AD 2018-20-13).

## Related Service Information Under 1 CFR Part 51

                    The FAA reviewed Boeing 767-200/300/300F/400ER Special Compliance Items/Airworthiness Limitations, D622T001-9-04, dated January 2020. This service information describes AWLs that include airworthiness limitation instructions (ALIs) and critical design configuration control limitations (CDCCLs) tasks related to fuel tank ignition prevention and the nitrogen generation system. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the                     **ADDRESSES**                     section.                

## FAA's Determination

The FAA is proposing this AD because the agency evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.

## Proposed AD Requirements

This proposed AD would require revising the existing maintenance or inspection program, as applicable, to incorporate the latest revision of the AWLs.

                    This proposed AD would require revisions to certain operator maintenance documents to include new actions (                    *e.g.,*                     inspections) and CDCCLs. Compliance with these actions and CDCCLs is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by this proposed AD, the operator may not be able to accomplish the actions described in the revisions. In this situation, to comply with 14 CFR 91.403(c), the operator must request approval for an alternative method of compliance according to paragraph (k) of this proposed AD.                          ( print page 11655)    

## Costs of Compliance

The FAA estimates that this proposed AD affects 500 airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed AD:

The FAA has determined that revising the existing maintenance or inspection program takes an average of 90 work-hours per operator, although the agency recognizes that this number may vary from operator to operator. Since operators incorporate maintenance or inspection program changes for their affected fleet(s), the FAA has determined that a per-operator estimate is more accurate than a per-airplane estimate. Therefore, the FAA estimates the average total cost per operator to be $7,650 (90 work-hours × $85 per work-hour).

## 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.

The FAA is 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

The FAA 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) Would not affect intrastate aviation in Alaska, and

(3) Would 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 

2. The FAA amends § 39.13 by adding the following new airworthiness directive: 

**The Boeing Company:**                         Docket No. FAA-2021-0099; Project Identifier AD-2020-01272-T.                    

## (a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) action by April 12, 2021.

## (b) Affected ADs

This AD affects the ADs specified in paragraphs (b)(1) through (7) of this AD.

(1) AD 2008-11-01 R1, Amendment 39-16145 (74 FR 68515, December 28, 2009) (AD 2008-11-01 R1).

(2) AD 2010-06-10, Amendment 39-16234 (75 FR 15322, March 29, 2010) (AD 2010-06-10).

(3) AD 2011-25-05, Amendment 39-16881 (77 FR 2442, January 18, 2012) (AD 2011-25-05).

(4) AD 2013-25-02, Amendment 39-17698 (79 FR 24541, May 1, 2014) (AD 2013-25-02).

(5) AD 2014-08-09, Amendment 39-17833 (79 FR 24546, May 1, 2014) (AD 2014-08-09).

(6) AD 2014-20-02, Amendment 39-17975 (79 FR 59102, October 1, 2014) (AD 2014-20-02).

(7) AD 2018-20-13, Amendment 39-19447 (83 FR 52305, October 17, 2018) (AD 2018-20-13).

## (c) Applicability

This AD applies to The Boeing Company Model 767-200, -300, -300F, and -400ER series airplanes, certificated in any category, having line numbers (L/N) 1 through 1200 inclusive.

## (d) Subject

Air Transport Association (ATA) of America Code 28, Fuel.

## (e) Unsafe Condition

This AD was prompted by significant changes made to the airworthiness limitations (AWLs) related to fuel tank ignition prevention and the nitrogen generation system. The FAA is issuing this AD to address the potential for ignition sources inside fuel tanks caused by latent failures, alterations, repairs, or maintenance actions, which, in combination with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of the airplane.

## (f) Compliance

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

## (g) Maintenance or Inspection Program Revision

Within 60 days after the effective date of this AD, revise the existing maintenance or inspection program, as applicable, to incorporate the information in Section A, including Subsections A.1, A.2, A.3, A.4, and A.5, of Boeing 767-200/300/300F/400ER Special Compliance Items/Airworthiness Limitations, D622T001-9-04, revision January 2020; except as provided by paragraph (h) of this AD. The initial compliance times for the airworthiness limitation instructions (ALI) tasks are within the applicable compliance times specified in paragraphs (g)(1) through (14) of this AD:

(1) For AWL No. 28-AWL-01, “External Wires Over Auxiliary (Center) Fuel Tank”: Within 144 months after the most recent inspection was performed as specified in AWL No. 28 AWL 01, or within 12 months after the effective date of this AD if no initial inspection has been performed or the last inspection date is unknown.

(2) For AWL No. 28-AWL-05, “Lightning Protection—Hydraulic Line Fuel Tank Penetration Bonding Path”: Within 25,000 flight hours or 72 months, whichever occurs first, since the most recent inspection was performed as specified in AWL No. 28-AWL-05, or within 30 days after the effective date of this AD if no initial inspection has been performed or the last inspection date is unknown.

(3) For AWL No. 28-AWL-18, “Fuel Quantity Indicating System (FQIS)—Out of Tank Wiring Lightning Shield to Ground Termination”: Within 144 months after the most recent inspection was performed as specified in AWL No. 28-AWL-18, or within 12 months after the effective date of this AD if no initial inspection has been performed or the last inspection date is unknown.

(4) For AWL No. 28-AWL-20, “Auxiliary (Center) Tank Override Fuel Pumps Auto Shutoff Circuit”: Within 12 months after the most recent inspection was performed as specified in AWL No. 28-AWL-20; or within 12 months after accomplishment of the actions specified in Boeing Service Bulletin 767-28A0083, or Boeing Service Bulletin 767-28A0084, as applicable; whichever is later. If no initial inspection was performed or the last inspection date is unknown, then within 30 days after the effective date of this AD.

                        (5) For AWL No. 28-AWL-21, “AC and DC Fuel Pump Fault Current Bonding Jumper Installation”: Within 72 months after the most recent inspection was performed as specified in AWL No. 28-AWL-21, or within 6 months after the effective date of this AD if no initial inspection has been performed or the last inspection date is unknown.                              ( print page 11656)    

(6) For AWL No. 28-AWL-27, “Over-Current and Arcing Protection Electrical Design Features Operation—AC Fuel Pump Ground Fault Interrupter (GFI)”: Within 12 months after the most recent inspection was performed as specified in AWL No. 28-AWL-27, or within 12 months after accomplishment of the actions specified in Boeing Service Bulletin 767-28A0085, whichever is later. If no initial inspection was performed or the last inspection date is unknown, then within 30 days after the effective date of this AD.

(7) For AWL No. 28-AWL-28, “Auxiliary (Center) Tank Override/Jettison Fuel Pump Failed On Protection System”: Within 12 months after the most recent inspection was performed as specified in AWL No. 28-AWL-28, or within 12 months after accomplishment of the actions specified in Boeing Service Bulletin 767-28A0085, whichever is later. If no initial inspection was performed or the last inspection date is unknown, then within 30 days after the effective date of this AD.

(8) For AWL No. 28-AWL-35, “Cushion Clamps and Teflon Sleeving Installed on Out-of-Tank Wire Bundles Installed on Brackets that are Mounted Directly on the Fuel Tanks”: Within 144 months after the most recent inspection was performed as specified in AWL No. 28-AWL-35 or within 144 months after accomplishment of the actions specified in Boeing Service Bulletin 767-57A0102, whichever is later. If no initial inspection was performed or the last inspection date is unknown, then within 12 months after the effective date of this AD.

(9) For AWL No. 28-AWL-37, “FQIS BITE Test (Auxiliary (Center) Tank Circuit Test)”: For Model 767-300F airplanes L/N 1094 and subsequent, within 750 flight hours after the most recent inspection was performed as specified in AWL No. 28-AWL-37, or within 30 days after the effective date of this AD if no initial inspection has been performed or the last inspection date is unknown.

(10) For AWL No. 28-AWL-38, “Fuel Level Sensing System (FLSS) Dry Capacitance Test”: For Model 767-300F airplanes L/N 1096 and subsequent, within 750 flight hours after the most recent inspection was performed as specified in AWL No. 28-AWL-38, or within 30 days after the effective date of this AD if no initial inspection has been performed or the last inspection date is unknown.

(11) For AWL No. 28-AWL-101, “Engine Fuel Suction Feed Operational Test”: Within 7,500 flight hours or 36 months, whichever occurs first since the most recent inspection was performed as specified in AWL No. 28-AWL-101, or within 30 days after the effective date of this AD if no initial inspection has been performed or the last inspection date is unknown.

(12) For AWL No. 28-AWL-102, “Fuel Quantity Indicating System (FQIS)—Low Fuel and Fuel Config Indication Test”: Within 750 flight hours after the most recent inspection was performed as specified in AWL No. 28-AWL-102; or within 750 flight hours after accomplishment of the actions specified in Boeing Service Bulletin 767-31-0295 or Boeing Service Bulletin 767-31-0302, as applicable; whichever is later. If no initial inspection was performed or the last inspection date is unknown, then within 30 days after the effective date of this AD.

(13) For AWL No. 47-AWL-04, “Nitrogen Generation System (NGS)—Nitrogen-Enriched Air (NEA) Distribution Ducting”: For L/N 993 and subsequent and all airplanes that have incorporated Boeing Service Bulletin 767-47-0001, within the applicable interval specified in AWL No. 47-AWL-04 since the most recent inspection was performed as specified in AWL No. 47-AWL-04. If no initial inspection was performed or the last inspection date is unknown, then within 4 months after the effective date of this AD.

(14) For AWL No. 47-AWL-05, “Nitrogen Generation System (NGS)—Cross Vent Check Valve”: For L/N 993 and subsequent and all airplanes that have incorporated Boeing Service Bulletin 767-47-0001, within the applicable interval specified in AWL No. 47-AWL-05 since the most recent inspection was performed as specified in AWL No. 47-AWL-05. If no initial inspection was performed or the last inspection date is unknown, then within 4 months after the effective date of this AD.

## (h) Additional Acceptable Wire Types and Sleeving

As an option, when accomplishing the actions required by paragraph (g) of this AD, the changes specified in paragraphs (h)(1) and (2) of this AD are acceptable.

(1) Where AWL No. 28-AWL-09 identifies wire types BMS 13-48, BMS 13-58, and BMS 13-60, the following acceptable wire types and cables can be added to AWL No. 28-AWL-09: MIL-W-22759/16, SAE AS22759/16 (formerly M22759/16), MIL-W-22759/32, SAE AS22759/32 (formerly M22759/32), MIL-W-22759/34, SAE AS22759/34 (formerly M22759/34), MIL-W-22759/41, SAE AS22759/41 (formerly M22759/41), MIL-W-22759/86, SAE AS22759/86 (formerly M22759/86), MIL-W-22759/87, SAE AS22759/87 (formerly M22759/87), MIL-W-22759/92, and SAE AS22759/92 (formerly M22759/92); and MIL-C-27500 and NEMA WC 27500 cables that are constructed from these military or SAE specification wire types, as applicable.

(2) Where AWL No. 28-AWL-09 identifies TFE-2X Standard wall for wire sleeving, the following sleeving materials are acceptable: Roundit 2000NX and Varglas Type HO, HP, or HM, Grade A.

## (i) No Alternative Actions, Intervals, or Critical Design Configuration Control Limitations (CDCCLs)

                        After the existing maintenance or inspection program has been revised as required by paragraph (g) of this AD, no alternative actions (                        *e.g.,*                         inspections), intervals, or CDCCLs may be used unless the actions, intervals, and CDCCLs are approved as an alternative method of compliance (AMOC) in accordance with the procedures specified in paragraph (k) of this AD.                    

## (j) Terminating Action for Certain AD Requirements

Accomplishment of the revision required by paragraph (g) of this AD terminates the requirements specified in paragraphs (j)(1) through (7) of this AD for that airplane:

(1) The revision required by paragraphs (g) and (h) of AD 2008-11-01 R1.

(2) The revision required by paragraph (h) of AD 2010-06-10.

(3) The revision required by paragraph (k) of AD 2011-25-05.

(4) The revision required by paragraph (n) of AD 2013-25-02.

(5) The revision required by paragraph (g) of AD 2014-08-09.

(6) The revision required by paragraph (h) of AD 2014-20-02.

(7) The revision required by paragraphs (i)(3)(i) and (ii) of AD 2018-20-13.

## (k) Alternative Methods of Compliance (AMOCs)

                        (1) The Manager, Seattle ACO Branch, 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 responsible Flight Standards Office, as appropriate. If sending information directly to the manager of the certification office, send it to the attention of the person identified in paragraph (l)(1) of this AD. Information may be emailed to:                         *9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.*

(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the responsible Flight Standards Office.

(3) An AMOC that provides an acceptable level of safety may be used for any repair, modification, or alteration required by this AD if it is approved by The Boeing Company Organization Designation Authorization (ODA) that has been authorized by the Manager, Seattle ACO Branch, FAA, to make those findings. To be approved, the repair method, modification deviation, or alteration deviation must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

## (l) Related Information

                        (1) For more information about this AD, contact Rebel Nichols, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3556; email:                         *rebel.nichols@faa.gov.*

                        (2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; telephone 562-797-1717; internet                         *https://www.myboeingfleet.com.*                         You may view this service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195.                    

Issued on February 12, 2021.

Lance T. Gant,

Director, Compliance & Airworthiness Division, Aircraft Certification Service.

[FR Doc. 2021-03858 Filed 2-25-21; 8:45 am]

BILLING CODE 4910-13-P