Document ID: FAA-2016-6143-0014
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Airbus SAS Airplanes
Posted Date: 2020-02-11T05:00Z

[Federal Register Volume 85, Number 28 (Tuesday, February 11, 2020)]
[Rules and Regulations]
[Pages 7655-7661]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-02512]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-6143; Product Identifier 2015-NM-028-AD; Amendment 
39-19821; AD 2020-01-15]
RIN 2120-AA64

Airworthiness Directives; Airbus SAS Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
Airbus SAS Model A300 B4-600, B4-600R, and F4-600R series airplanes, 
and Model A300 C4-605R Variant F airplanes (collectively called Model 
A300-600 series airplanes), and certain Model A310 series airplanes. 
This AD was prompted by the FAA's analysis of the fuel system reviews 
on these models conducted by the manufacturer. This AD requires 
modifying the fuel quantity indicating system (FQIS) to prevent 
development of an ignition source inside the center fuel tank due to 
electrical fault conditions. This AD also provides alternative actions 
for cargo airplanes. The FAA is issuing this AD to address the unsafe 
condition on these products.

DATES: This AD is effective March 17, 2020.

ADDRESSES:

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-2016-
6143; 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 final rule, the regulatory evaluation, any comments received, and 
other information. The address for Docket Operations is U.S. Department 
of Transportation, Docket Operations, M-30, West Building Ground Floor, 
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Dan Rodina, Aerospace Engineer, 
International Section, Transport Standards Branch, FAA, 2200 South 
216th St., Des Moines, WA 98198; telephone and fax 206-231-3225.

SUPPLEMENTARY INFORMATION:

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to all Airbus SAS Model 
A300 B4-600, B4-600R, and F4-600R series airplanes, and Model A300 C4-
605R Variant F airplanes (collectively called Model A300-600 series 
airplanes), and certain Model A310 series airplanes. The NPRM published 
in the Federal Register on May 3, 2016 (81 FR 26493). The NPRM was 
prompted by the FAA's analysis of the fuel system reviews on these 
models conducted by the manufacturer. The NPRM proposed to require 
modifying the FQIS to prevent development of an ignition source inside 
the center fuel tank due to electrical fault conditions. The NPRM also 
proposed alternative actions for cargo airplanes.
    The FAA is issuing this AD to address ignition sources inside the 
center fuel tank, which, in combination with flammable fuel vapors, 
could result in a fuel tank explosion and consequent loss of the 
airplane.

Comments

    The FAA gave the public the opportunity to participate in 
developing this final rule. The following presents the comments 
received on the NPRM and the FAA's response to each comment.

Support for NPRM

    The Air Line Pilots Association, International (ALPA) and National 
Air Traffic Controllers Association (NATCA) supported the intent of the 
NPRM. Additional comments from NATCA are addressed below.

[[Page 7656]]

Requests To Withdraw NPRM: EASA's Different Risk Assessment Policy

    Airbus and the European Aviation Safety Agency (EASA) noted 
differences between EASA's risk assessment policy and that of the FAA. 
Based on its own criteria, EASA concluded that there is no unsafe 
condition, and that in the absence of a TARAM (transport airplane risk 
assessment methodology) analysis, EASA concluded the NPRM was based on 
noncompliance with Special Federal Aviation Regulation (SFAR) 88--Fuel 
Tank System Fault Tolerance Evaluation Requirements, to 14 CFR part 21 
(66 FR 23086, May 7, 2001), and, more specifically, with 14 CFR 
25.981(a)(3) as amended by amendment 25-102 (66 FR 23086, May 7, 2001), 
rather than a direct unsafe condition. The commenters asserted that 
Airbus has shown that the failure condition described in the NPRM is 
extremely improbable and not unsafe according to EASA policy. The 
commenters therefore considered the proposed corrective actions 
unnecessary.
    The FAA infers that the commenters would like the NPRM withdrawn. 
The FAA disagrees with this proposal. The FAA does not agree that the 
NPRM was based simply on a noncompliance with 14 CFR 25.981(a) 
identified from the manufacturer's fuel system reviews. This final rule 
addresses an unsafe condition identified by the FAA. The FAA determined 
that an unsafe condition exists using the criteria in FAA Policy 
Memorandum ANM100-2003-112-15, ``SFAR 88--Mandatory Action Decision 
Criteria,'' dated February 25, 2003.\1\ That policy was used to 
evaluate the noncompliant design areas identified in the manufacturer's 
fuel system reviews and to determine which noncompliance issues were 
unsafe conditions that required corrective action under 14 CFR part 39. 
The FAA's unsafe condition determination was not based on an assessment 
of average risk or total fleet risk, but rather was driven by the 
qualitative identification of an unacceptable level of individual risk 
that exists on flights that are anticipated to occur with a preexisting 
latent in-tank failure condition and with a flammable center fuel tank. 
For these reasons, and based on further detailed responses to similar 
comments in supplemental NPRM (SNPRM) Docket No. FAA-2012-0187 (80 FR 
9400, February 23, 2015), and in the subsequently issued final rule, AD 
2016-07-07, Amendment 39-18452 (81 FR 19472, April 5, 2016) (``AD 2016-
07-07''), which addressed the same unsafe condition for Boeing Model 
757 airplanes, the FAA has determined that it is necessary to issue 
this final rule.
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    \1\ http://rgl.faa.gov/Regulatory_and_Guidance_Library/
rgPolicy.nsf/0/dc94c3a46396950386256d5e006aed11/$FILE/Feb2503.pdf.
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Request To Withdraw NPRM: Probability Analysis Inconsistent With 
Regulatory Requirements

    Airlines for America and the Cargo Airline Association, in 
consolidated comments (A4A/CAA), United Parcel Service (UPS), and FedEx 
stated that the assumption of a single failure regardless of 
probability is inconsistent with 14 CFR part 25 regulatory 
requirements. The commenters referred to the phrase ``regardless of 
probability'' associated with single failures. A4A/CAA and UPS 
acknowledged that the term is used with single failures in FAA Advisory 
Circular (AC) 25.981-1C,\2\ ``Fuel Tank Ignition Source Prevention 
Guidelines,'' but since that term does not appear in 14 CFR 
25.981(a)(3), the commenters considered its use arbitrary, possibly 
introducing additional requirements not included in that section. FedEx 
also considers a ``worst anticipated flight'' as a flight with a latent 
failure. FedEx added that unless the remote likelihood of a latent 
failure is considered under 14 CFR 25.981(a)(3), the probability of a 
catastrophic event is exaggerated. A4A/CAA and UPS stated that the 
``worst reasonably anticipated flight'' is a flight with a latent FQIS 
failure and a high-flammability tank, and this ``latent plus one'' 
failure--regardless of probability of a single failure--is not 
consistent with 14 CFR 25.981(a)(3).
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    \2\ https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_25.981-1C.pdf.
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    The FAA infers that the commenters would like the NPRM withdrawn. 
The FAA disagrees with this proposal, and disagrees with the 
commenters' assertions regarding the intent of 14 CFR 25.981(a)(3). The 
intent of the single failure clause in 14 CFR 25.981(a)(3) is to set a 
general fail-safe minimum safety standard for the prevention of fuel 
tank ignition sources. The intent of the latent failure plus single 
failure clause in 14 CFR 25.981(a)(3) is to explicitly set a 
requirement for a fail-safe configuration (with respect to ignition 
sources) to be provided on flights that occur with any latent condition 
that cannot be shown to be extremely remote. Such flights are 
reasonably anticipated to occur multiple times in a fleet of aircraft 
of a given type, and those flights are required to be fail safe. These 
requirements were included in 14 CFR 25.981(a)(3) in recognition of the 
fact that simply providing a system that meets the extremely improbable 
average risk requirement of 14 CFR 25.1309(b) is not sufficient to 
prevent all catastrophic accidents. Systems that provide dual 
redundancy rather than triple redundancy, and that have one or both 
features susceptible to latent failure conditions, may pass the average 
risk test of 14 CFR 25.1309(b). However, such systems would not be fail 
safe on flights with latent failures, and may have an average 
probability of catastrophic failure--on those non-fail-safe flights--
that is 100 or even 1,000 times worse than the overall risk on an 
average transport airplane flight. This would not meet the expectation 
of the public or Congress for the level of safety on each transport 
airplane flight. 14 CFR 25.981(a)(3) sets standards that are intended 
to prevent such high-risk flights and non-fail-safe flights.
    The intent of 14 CFR 25.981(a)(3) is clear from the plain language 
of the rule. In every system safety analysis requirement in a 14 CFR 
part 25 regulation where the FAA intends a probabilistic condition or 
modifier to be associated with a requirement, that condition or 
modifier is explicitly stated in the wording of the rule in qualitative 
terms that are further defined in guidance material. Absence of such 
wording is clear evidence of the absence of an intended probabilistic 
condition or modifier. In other words, in the absence of a specific 
probabilistic qualifier, the intent of prescriptive prohibition is that 
it applies ``regardless of probability.''
    The intent of 14 CFR 25.981(a)(3) with respect to the ``regardless 
of probability'' intent questioned by the commenters was also stated 
clearly in the preamble of the NPRM for 14 CFR 25.981, amendment 25-
102. That preamble to the NPRM stated, in pertinent part, as follows.

    This proposal would also add a new paragraph (a)(3) to require 
that a safety analysis be performed to demonstrate that the presence 
of an ignition source in the fuel tank system could not result from 
any single failure, from any single failure in combination with any 
latent failure condition not shown to be extremely remote, or from 
any combination of failures not shown to be extremely improbable. 
These new requirements define three scenarios that must be addressed 
in order to show compliance with the proposed paragraph (a)(3). The 
first scenario is that any single failure, regardless of the 
probability of occurrence of the failure, must not cause an ignition 
source. The second scenario is that any single failure, regardless 
of the probability occurrence, in combination with any latent 
failure condition not shown to be at least extremely remote (i.e., 
not shown to be extremely remote or extremely improbable), must not 
cause an ignition source. The third scenario is that any combination 
of failures not shown to be

[[Page 7657]]

extremely improbable must not cause an ignition source.

The preamble to the final rule for amendment 25-102 made a nearly 
identical statement, including the same uses of the phrase ``regardless 
of probability.''
    The FAA does not agree with FedEx's related comment that the 
assumption of a preexisting failure on the worst anticipated flight 
``exaggerates the probability of a catastrophic event.'' In fact, 
FedEx's apparently preferred method to characterize the probability of 
a catastrophic event as equal to the average probability of the event 
on all flights fails to assess the degree to which risk is concentrated 
on flights with latent failures, and simply does not assess the actual 
risk on such flights. The FAA has previously determined, in the 
promulgation of amendment 25-102, in development of the AD decision 
policy for issues identified through SFAR 88 reviews, and in the 
general assessment of potential unsafe conditions on transport 
airplanes under the TARAM policy, that assessment of risk on the worst 
anticipated flights is fundamental to providing a minimum acceptable 
level of safety on each reasonably anticipated flight as expected by 
Congress and the public.
    No change to the AD was made in response to these comments.

Request To Withdraw NPRM: Reconsider Center Wing Fuel Tank Flammability 
Exposure Time

    A4A/CAA, UPS, and Airbus requested that the FAA withdraw the NPRM 
based on their assertion that the current design of the center wing 
fuel tank is safe. According to the commenters, Airbus has shown that 
the center wing fuel tank does not meet the policy criteria set forth 
for a high-flammability exposure time fuel tank in SFAR 88.
    The FAA disagrees with the commenters' request. Airbus originally 
submitted its flammability exposure time analysis in accordance with 
FAA Policy Memorandum ANM100-2003-112-15, as requested by the FAA and 
not in response to SFAR 88 since the submission was not a requirement 
of SFAR 88. As a result of the original Airbus analysis, the center 
wing fuel tanks on Model A300-600 and A310 series airplanes were 
categorized as having high fleet average flammability exposure time. In 
the resubmitted analysis, however, Airbus did not follow FAA Policy 
Memorandum ANM100-2003-112-15, when it incorrectly adjusted the 
standardized FAA Monte Carlo analysis to account for cargo-only 
operations in the U.S. This resulted in a significant deviation from 
the FAA Monte Carlo analysis used to consistently evaluate fleet 
average flammability exposure time for numerous airplane models across 
multiple manufacturers. Deviating from the standardized modeling 
technique, as Airbus has done, nullifies the basis for comparison of 
the Airbus analysis results to the 7-percent criterion established for 
determining whether a fuel tank has high- or low-flammability exposure 
time per the FAA Policy Memorandum ANM100-2003-112-15. As with any 
standardized testing or analysis methods, deviating from the 
standardized model and input affects the validity and applicability of 
the standardized pass/fail criteria. The 7-percent criterion is valid 
only when the standardized FAA Monte Carlo method is used without 
deviation; for this reason, the FAA does not accept an analysis 
developed with variables to account for specific fleet or subfleet 
operations. The FAA, based on its application of Policy Memorandum 
ANM100-2003-112-15, has therefore determined that it is necessary to 
proceed with issuance of this final rule.

Request To Withdraw NPRM: No New Data Since Fuel Tank Flammability 
Reduction (FTFR) Rulemaking

    A4A/CAA and UPS requested that the FAA withdraw the NPRM based on a 
lack of new data since the issuance of the FTFR rule (73 FR 42444, July 
21, 2008). The commenters referred to the FTFR rule and decision to not 
require flammability reduction means (FRM) for all-cargo airplanes, and 
the FAA's intent to gather additional data and consideration of further 
rulemaking if flammability of these airplanes is excessive. The 
commenters also referred to the FAA's response to comments in the 
preamble to the SNPRM for Docket No. FAA-2012-0187, which documented 
the FAA's decision on applicability of FRM and cost estimates. The 
commenters stated that the FAA response was misleading and not factual 
since manufacturers did not begin detailed designs to address the 
proposed unsafe condition until after the FTFR rule was published. The 
commenters added that the FAA did not discuss other changes to the FQIS 
system in the FTFR rule.
    The FAA disagrees with the commenters' request. In the preamble to 
the FTFR rule, the FAA indicated the possibility of later changing its 
position and proposing inerting for cargo airplanes if later data shows 
the flammability on cargo airplanes is excessive. The determination 
that including cargo airplanes in the FTFR rule's requirement to 
retrofit airplanes with FRM would not be cost effective was based in 
part on the assumption that corrective actions would be required for 
the FQIS unsafe condition identified under FAA Policy Memorandum 
ANM100-2003-112-15. Since that determination, manufacturers have 
updated their cost estimates based on subsequent detailed design work. 
The FAA responded to similar comments in the preamble to the final rule 
for AD 2016-07-07. The FAA has therefore determined that it is 
necessary to proceed with this final rule.

Request To Withdraw NPRM: Arbitrary and Inconsistent Wire Separation 
Standards

    A4A/CAA, FedEx, and UPS requested that the FAA withdraw the NPRM 
based on a lack of consistent design standards for FQIS wire 
separation. The commenters assumed that the approved standard for the 
retrofit is a 2-inch wire separation minimum, which the commenters 
considered arbitrary and inconsistently applied. The commenters 
reported that the amount of wiring capable of meeting that separation 
standard varies widely among airplane models. A4A/CAA and UPS also 
acknowledged that other separation methods were used in areas not 
meeting the 2-inch wire separation requirement.
    The FAA disagrees with the commenters' request to withdraw the 
NPRM. Because of configuration differences between different airplane 
designs, as the commenter also notes, the FAA has not defined a 
universal minimum standard for wiring design, including wire 
separation, as explained in paragraph 8.3.3 of AC 25.981-1D: \3\
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    \3\ https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_25.981-1D.pdf.

    Wiring designs used on transport category airplanes vary 
significantly between manufacturers and models; therefore, it is not 
possible to define a specific, universal, separation distance, or 
the characteristics of physical barriers between wire bundles, to 
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protect critical wiring from damage.

    AC 25.981-1D also notes the following:

    Some areas of an airplane may have localized areas where 
maintaining a general physical separation distance is not feasible. 
This is especially true in smaller transport category airplanes or 
in areas where wiring spans the wing-to-body join of larger 
transport airplanes. In those areas that limit separation distance, 
additional means of ensuring physical separation and protection of 
the wiring may be necessary. Testing and/or analysis used to show 
that the reduced separation distance is acceptable should be 
conservative and consider the worst possible failure condition not 
shown to be extremely improbable. The applicant should

[[Page 7658]]

substantiate that the means to achieve the reduced separation 
provides the necessary level of protection for wire-related failures 
and electromagnetic effects.

    In addition, the FAA provided a detailed response to similar 
comments in the preamble to the final rule for AD 2016-07-07. The FAA 
has therefore determined that it is necessary to proceed with issuance 
of this final rule.

Request To Withdraw NPRM: NPRM Arbitrary and Inconsistently Applied

    A4A/CAA and UPS requested that the FAA withdraw the NPRM based on 
the commenters' assertion that the NPRM is arbitrary and inconsistently 
applied. The commenters noted that airplanes with FRM are not included 
in the applicability, and the NPRM would therefore not fully address 
the unsafe condition. The commenters added that the distinction between 
high- and low-flammability exposure time fuel tanks as used in the NPRM 
is arbitrary. The commenters stated that an arbitrary differentiation 
of high/low flammability as decisional criteria for the need for 
corrective action does not take into account the actual probability of 
the impact of the difference in flammability on the potential of 
catastrophic failure. The commenters also stated that allowing the 
proposed alternative actions for cargo airplanes does not fully address 
the unsafe condition in the NPRM. The commenters referenced the FAA's 
response to comments in AD 2016-07-07 regarding this issue.
    The FAA disagrees with the assertion that the NPRM is arbitrary and 
inconsistent. The NPRM follows defined policy in FAA Policy Memorandum 
ANM100-2003-112-15, and consistently applies the policy to several 
airplane models with similar unsafe conditions, similar to AD 2016-07-
07. The FAA defined the difference between low- and high-flammability 
exposure time fuel tanks based on recommendations from the Aviation 
Rulemaking Advisory Committee Fuel Tank Harmonization Working Group 
(FTHWG). The preamble to the final rule for amendment 25-102, which 
amended 14 CFR 25.981, defines this difference:

    The level of flammability defined in the proposal was 
established based upon comparison of the safety record of center 
wing fuel tanks that, in certain airplanes, are heated by equipment 
located under the tank, and unheated fuel tanks located in the wing. 
The FTHWG concluded that the safety record of fuel tanks located in 
the wings was adequate and that if the same level could be achieved 
in center wing fuel tanks, the overall safety objective would be 
achieved.

    In the response to comments in the preamble to the final rule for 
AD 2016-07-07 referenced by the commenters, the FAA described why FRM 
or alternative actions for cargo airplanes provide an acceptable level 
of safety, even if they do not completely eliminate the non-compliance 
with 14 CFR 25.981(a)(3).
    The FAA has determined that it is necessary to proceed with 
issuance of this final rule.

Request To Withdraw NPRM: Insufficient Justification for AD

    Based on an assertion that the FAA did not sufficiently explain how 
the unsafe condition justifies AD rulemaking, UPS requested that the 
FAA withdraw the NPRM. UPS stated that the FTFR rule did not suggest 
that any future modifications of FQIS systems had been considered. UPS 
contended that all-cargo operators were surprised and prejudiced by 
costly proposed FQIS modifications that are unsupported by both an 
updated risk assessment and full cost/benefit analysis that consider 
the pertinent facts. UPS alleged that the FAA did not fully explain or 
justify its decision making for the NPRM, and concluded that the NPRM 
is arbitrary and does not reflect properly reasoned agency action.
    The FAA disagrees with the commenter's request. The justification 
for this AD was extensively described in the NPRM, in response to 
comments described elsewhere in this final rule, and in the AD 
rulemaking actions related to AD 2016-07-07, as explained in the 
response to ``Request to Withdraw NPRM: Probability Analysis 
Inconsistent with Regulatory Requirements'' in this final rule. The FAA 
has therefore determined that it is necessary to proceed with issuance 
of this final rule.

Request for Safety Risk Assessment and Cost-Benefit Analysis

    FedEx requested that a safety risk assessment and cost-benefit 
analysis be done to justify the required modification. FedEx asserted 
that the NPRM did not provide the reduction in probability of a fuel 
tank explosion if the modification is done, but FedEx noted that 
evidence should exist to support the modification since there can be 
multiple modifications required, and a cost-benefit analysis should be 
done showing that the modification provides an acceptable level of 
safety.
    The FAA disagrees with the commenter's request. This final rule 
addresses an unsafe condition as described in 14 CFR part 39. The FAA 
previously provided cost estimates in the NPRM and described why 
corrective actions are necessary to address the unsafe condition. In 
addition, the FAA's detailed response to similar comments and the 
description of the FAA's risk assessment in the preamble of the SNPRM 
for Docket No. FAA-2012-0187, and in the preamble to the final rule for 
the subsequently issued AD 2016-07-07, adequately address these issues. 
Therefore, the FAA has not changed this final rule regarding this 
issue.

Request To Revise Description of Determination of Unsafe Condition

    Airbus requested that the FAA revise the NPRM to state that the 
unsafe condition is based on reviews by the FAA, not the manufacturer. 
Based on the fuel tank safety reviews and its analysis of real-world 
data specific to cargo aircraft operated in the U.S., Airbus concluded 
that the ``latent plus one condition'' associated with a high-
flammability exposure time fuel tank does not exist.
    The FAA partially agrees with the commenter's request. As 
previously discussed, the FAA considers the center wing fuel tanks of 
Model A300-600 and Model A310 airplanes as high-flammability exposure 
time fuel tanks; therefore, the criteria for an unsafe condition are 
met as described in FAA Policy Memorandum ANM100-2003-112-15. However, 
the FAA agrees to clarify that the unsafe condition was determined by 
the FAA's analysis of the manufacturer's fuel system reviews and has 
revised this final rule accordingly.

Request To Remove Model A310-200

    Airbus requested that the FAA remove Model A310-200 airplanes from 
the applicability of the proposed AD. Airbus stated that no Model A310-
200 airplanes have been operational under 14 CFR part 135 since April 
2016, and Airbus has no plans to develop modifications to the aircraft 
wiring for those airplanes.
    The FAA agrees with the commenter's request to remove Model A310-
200 airplanes from the applicability of the AD. Since the NPRM was 
issued, all Model A310-200 airplanes have been removed from service. 
The FAA has revised this AD accordingly.

Request To Include Service Information

    Airbus reported that it is developing inspection service bulletins 
for Model A300-600 and A310 series airplanes as a method of compliance 
with paragraph (h)(1) of the proposed AD. Airbus also reported that it 
is developing a modification service bulletin for Model A300-600 series 
airplanes as a method

[[Page 7659]]

of compliance with paragraph (h)(2) of the proposed AD.
    The FAA infers that Airbus would like the FAA to include this 
service information in this AD. Because these service bulletins are not 
yet approved or available, the FAA cannot identify them as the source 
of service information for the referenced requirements in this AD. 
However, if Airbus releases service information that adequately 
addresses the unsafe condition regarding the inspection and/or 
modification requirements, the FAA may consider the service information 
as an alternative method of compliance (AMOC) for this AD. The FAA has 
not changed this AD regarding this issue.

Request To Change Compliance Time

    A4A/CAA, FedEx, and Airbus requested that the FAA extend the 
compliance time from 60 months to 72 months for the modification 
specified in the proposed AD. Airbus and FedEx stated that the 
compliance time should match that of AD 2016-07-07 because the unsafe 
condition and corrective actions are similar. Airbus stated that the 
additional time is appropriate due to the modification's anticipated 
complexity, development time and cost, cost of kits, and airplane 
downtime. In addition, Airbus and FedEx both expressed concerns about 
the feasibility of the modification due to the potential effects of 
existing FQIS modifications through supplemental type certificates. 
A4A/CAA stated that although service information was not yet available, 
the compliance time should align with major maintenance schedules, but 
should be not less than 72 months after service information is 
available.
    Conversely, NATCA recommended that the FAA reject requests for a 
compliance time longer than 5 years as proposed in the NPRM. Assuming 
final rule issuance in 2016, NATCA stated that a 5-year compliance time 
would result in required compliance by 2021--25 years after the TWA 
Flight 800 fuel tank explosion that led to the requirements in SFAR 88, 
and 20 years after issuance of SFAR 88.
    The FAA agrees with the commenters' requests to extend the 
compliance time, and disagrees with NATCA's request. The FAA received 
similar requests to extend the compliance time from several commenters 
regarding the NPRMs for the FQIS modification on other airplanes. The 
FAA disagrees with establishing a compliance time based on issuance of 
the service information that is not yet approved or available. The FAA 
has determined that a 72-month compliance time is appropriate and will 
provide operators adequate time to prepare for and perform the required 
modifications without excessive disruption of operations. The FAA has 
determined that the requested moderate increase in compliance time will 
continue to provide an acceptable level of safety. The FAA has changed 
paragraphs (g) and (h)(2) of this AD accordingly.

Request To Clarify Certification Basis for Modification Requirements

    NATCA recommended that the FAA revise paragraph (g) of the proposed 
AD to clearly state that the required FQIS design changes must comply 
with the fail-safe requirements of 14 CFR 25.901(c), amendment 25-46 
(43 FR 50597, October 30, 1978), and 14 CFR 25.981(a) and (b), 
amendment 25-102; NATCA added that these provisions are required by 
SFAR 88.
    The FAA infers that NATCA is proposing that the certification basis 
of the design changes to the FQIS system design be at the amendment 
levels cited above. The FAA further infers that NATCA proposes that the 
FAA require the entire FQIS system design to comply at those amendment 
levels rather than allowing only a portion of the system to comply with 
those amendments. The FAA partially agrees with NATCA's request. The 
FAA agrees that the design change must comply with the applicable 
certification basis, because design changes are required to comply with 
the applicable certification basis under part 21. The FAA disagrees, 
however, with identifying the specific certification basis in this AD, 
because it varies by design. In addition, the FAA previously identified 
in the preamble of the SNPRM for AD 2016-07-07 in the response to 
comments under ``Requests To Withdraw NPRM (77 FR 12506, March 1, 2012) 
Based on Applicability'' that the option for cargo airplanes will 
require a partial exemption from 14 CFR 25.901(c) and 25.981(a)(3). The 
partial exemption is needed because portions of the FQIS would remain 
unmodified, and the overall system would therefore still not fully 
comply with those regulations. The FAA has already granted such 
exemptions for other airplane models. Identifying these amendments as 
required would also not take into account exceptions (reversions to 
earlier versions of regulations) granted in the certification basis 
under 14 CFR 21.101. The FAA has not changed this AD regarding this 
issue.

Request To Address Unsafe Condition on All Fuel Tanks

    NATCA recommended that the FAA require design changes that 
eliminate unsafe FQIS failure conditions on all fuel tanks on the 
affected models, regardless of fuel tank location or the percentage of 
time the fuel tank is flammable. NATCA referred to four fuel tank 
explosions in low-flammability exposure time fuel tanks identified by 
the FAA during FTFR rulemaking. NATCA stated that neither FRM nor 
alternative actions for cargo airplanes (e.g., BITE checks (checks of 
built-in test equipment) followed by applicable repairs before further 
flight and modification of the center fuel tank FQIS wiring within 72 
months) would bring the airplane into full regulatory compliance. NATCA 
added that the combination of failures described in the NPRM meets the 
criteria for ``known combinations'' of failures that require corrective 
action in FAA Policy Memorandum ANM100-2003-112-15.
    The FAA disagrees with the commenter's request. The FAA has 
determined that according to Policy Memorandum ANM100-2003-112-15, the 
failure condition for the airplanes affected by this AD should not be 
classified as a ``known combination.'' While the FQIS design 
architecture is similar to that of the early Boeing Model 747 
configuration that is suspected of contributing to the TWA Flight 800 
fuel tank explosion, significant differences exist in the design of 
FQIS components and wire installations between the affected Airbus SAS 
models and the early Model 747 airplanes such that the intent of the 
``known combinations'' provision for low-flammability fuel tanks in the 
policy memorandum is not applicable. Therefore, this AD affects only 
the identified Airbus airplanes with high-flammability exposure time 
fuel tanks, as specified in paragraph (c) of this AD. The FAA provided 
a detailed response to similar comments in the preamble of the final 
rule for AD 2016-07-07. The FAA has not changed this final rule 
regarding this issue.

Request To Require Modifications on All Production Airplanes

    NATCA recommended that the FAA require designs that comply with 14 
CFR 25.901(c) and 25.981(a)(3) on all newly produced transport 
airplanes. NATCA stated that continuing to grant exemptions to 14 CFR 
25.901(c), as amended by amendment 25-40 (42 FR 15042, March 17, 1977), 
and 14 CFR 25.981(a)(3), as amended by amendment 25-102, has allowed 
continued production of thousands of airplanes with this known unsafe 
condition.
    The FAA disagrees with the commenter's request. The recommendation 
to require production airplanes to fully comply with 25.901(c) and 
25.981(a)(3) is outside the scope of

[[Page 7660]]

this rulemaking. This AD applies only to Model A300-600 and Model A310 
airplanes, which are no longer in production. The FAA has not changed 
this final rule regarding this issue.

Request To Require Design Changes From Manufacturers

    NATCA recommended that the FAA follow the agency's compliance and 
enforcement policy to require manufacturers to develop the necessary 
design changes soon enough to support operators' ability to comply with 
the proposed requirements. NATCA noted that SFAR 88 required 
manufacturers to develop all design changes for unsafe conditions 
identified by their SFAR 88 design reviews by December 2002, or within 
an additional 18 months if the FAA granted an extension.
    The FAA acknowledges the commenter's concerns. However, any 
enforcement action is outside the scope of this rulemaking. The FAA has 
not changed this final rule regarding this issue.

Clarification of BITE Check Compliance Time

    The FAA has revised paragraph (h)(1) of this AD to clarify the 
compliance time for the BITE check relative to the requirement to 
record the fault codes. The FAA recognized that operators might 
interpret the proposed requirements for alternative actions for cargo 
airplanes as allowing additional flights prior to performing the BITE 
check after first recording the fault codes. The FAA intended for 
operators to perform the BITE check immediately after recording the 
fault codes to address both the fault codes that exist prior to 
performing the BITE check and any new codes that are identified during 
the BITE check.

Additional Compliance Time Change

    For consistency with similar ADs related to FQIS, the FAA has 
revised paragraph (h)(1) of this AD to change the repetitive interval 
for recording the existing fault codes stored in the fuel quantity 
indicating (FQI) computer and performing the BITE check from ``not to 
exceed 650 flight hours'' to ``not to exceed 750 flight hours.'' The 
FAA has determined that this change continues to provide an acceptable 
level of safety.

Conclusion

    The FAA reviewed the relevant data, considered the comments 
received, and determined that air safety and the public interest 
require adopting this final rule with the changes described previously 
and minor editorial changes. The FAA has determined that these minor 
changes:
     Are consistent with the intent that was proposed in the 
NPRM for addressing the unsafe condition; and
     Do not add any additional burden upon the public than was 
already proposed in the NPRM.
    The FAA also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this final 
rule.

Costs of Compliance

    The FAA estimates that this AD affects 122 airplanes of U.S. 
registry.
    The FAA also estimates that it would take about 1,200 work-hours 
per product to comply with the basic requirements of this AD. The 
average labor rate is $85 per work-hour. The FAA has received no 
definitive data that would enable us to provide cost estimates for the 
parts needed to do the required actions. Based on these figures, The 
FAA estimates the labor cost of this AD on U.S. operators to be 
$12,444,000, or $102,000 per product.
    The FAA has not received definitive information on the costs for 
the alternative wire separation modification specified in this AD. The 
cost for this action in similar rulemaking on other airplanes, however, 
suggests that this modification could take about 74 work-hours, with 
parts costing about $10,000, for a total estimated cost to U.S. 
operators of $16,290 per product.
    The FAA estimates that the repetitive FQIS tank circuit checks 
associated with the alternative wire separation modification would take 
about 1 work-hour per check. The FAA estimates the cost of this check 
on U.S. operators to be $85 per product, per check.

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.
    This AD is issued in accordance with authority delegated by the 
Executive Director, Aircraft Certification Service, as authorized by 
FAA Order 8000.51C. In accordance with that order, issuance of ADs is 
normally a function of the Compliance and Airworthiness Division, but 
during this transition period, the Executive Director has delegated the 
authority to issue ADs applicable to transport category airplanes and 
associated appliances to the Director of the System Oversight Division.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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 that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Will not affect intrastate aviation in Alaska, 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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec.  39.13   [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2020-01-15 Airbus SAS: Amendment 39-19821; Docket No. FAA-2016-6143; 
Product Identifier 2015-NM-028-AD.

(a) Effective Date

    This AD is effective March 17, 2020.

(b) Affected ADs

    None.

[[Page 7661]]

(c) Applicability

    This AD applies to all Airbus SAS airplanes, certificated in any 
category, identified in paragraphs (c)(1) through (5) of this AD.
    (1) Model A300 B4-601, B4-603, B4-620, and B4-622 airplanes.
    (2) Model A300 B4-605R and B4-622R airplanes.
    (3) Model A300 F4-605R and F4-622R airplanes.
    (4) Model A300 C4-605R Variant F airplanes.
    (5) Model A310-304, -322, -324, and -325 airplanes.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by the FAA's analysis of fuel system 
reviews on the affected airplanes conducted by the manufacturer. The 
FAA is issuing this AD to prevent ignition sources inside the center 
fuel tank, 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) Modification

    Within 72 months after the effective date of this AD, modify the 
fuel quantity indicating system (FQIS) to prevent development of an 
ignition source inside the center fuel tank due to electrical fault 
conditions, using a method approved by the Manager, International 
Section, Transport Standards Branch, FAA.

(h) Alternative Actions for Cargo Airplanes

    For airplanes used exclusively for cargo operations: As an 
alternative to the requirements of paragraph (g) of this AD, do the 
actions specified in paragraphs (h)(1) and (h)(2) of this AD. To 
exercise this alternative, operators must perform the first 
inspection required under paragraph (h)(1) of this AD within 6 
months after the effective date of this AD. To exercise this 
alternative for airplanes returned to service after conversion of 
the airplane from a passenger configuration to an all-cargo 
configuration more than 6 months after the effective date of this 
AD, operators must perform the first inspection required under 
paragraph (h)(1) of this AD prior to further flight after the 
conversion.
    (1) Within 6 months after the effective date of this AD, record 
the existing fault codes stored in the fuel quantity indicating 
(FQI) computer, and before further flight thereafter, do a BITE 
check (check of built-in test equipment) of the FQI computer, using 
a method approved by the Manager, International Section, Transport 
Standards Branch, FAA. If any fault code is recorded prior to the 
BITE check or as a result of the BITE check, before further flight, 
do all applicable repairs and repeat the BITE check until a 
successful test is performed with no fault found, using a method 
approved by the Manager, International Section, Transport Standards 
Branch, FAA. Repeat these actions thereafter at intervals not to 
exceed 750 flight hours. Modification as specified in paragraph 
(h)(2) of this AD does not terminate the repetitive BITE check 
requirement of this paragraph.
    (2) Within 72 months after the effective date of this AD, modify 
the airplane by separating FQIS wiring that runs between the FQI 
computer and the center fuel tank wall penetrations, including any 
circuits that might pass through a main fuel tank, from other 
airplane wiring that is not intrinsically safe, using methods 
approved by the Manager, International Section, Transport Standards 
Branch, FAA.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, International Section, Transport Standards 
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 
local Flight Standards District Office, as appropriate. If sending 
information directly to the manager of the International Section, 
send it to the attention of the person identified in paragraph (j) 
of this AD.
    (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.

(j) Related Information

    For more information about this AD, contact Dan Rodina, 
Aerospace Engineer, International Section, Transport Standards 
Branch, FAA, 2200 South 216th St., Des Moines, WA 98198; telephone 
and fax 206-231-3225.

(k) Material Incorporated by Reference

    None.

    Issued on January 31, 2020.
Michael Kaszycki,
Acting Director, System Oversight Division, Aircraft Certification 
Service.
[FR Doc. 2020-02512 Filed 2-10-20; 8:45 am]
BILLING CODE 4910-13-P