Document ID: FAA-2010-1167-0047
Agency: faa
Document Type: Rule
Title: Airworthiness Directives Legal Interpretation
Posted Date: 2016-04-27T04:00Z

[Federal Register Volume 81, Number 81 (Wednesday, April 27, 2016)]
[Rules and Regulations]
[Pages 24693-24696]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-09667]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-1167]

Airworthiness Directives Legal Interpretation

AGENCY: Federal Aviation Administration, DOT.

ACTION: Airworthiness directives legal interpretation.

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SUMMARY: The Federal Aviation Administration is issuing a legal 
interpretation on regulations applicable to airworthiness directives. 
This legal interpretation responds to questions asked by an Aviation 
Rulemaking Committee and is intended to resolve certain issues for the 
public.

[[Page 24694]]

DATES: April 27, 2016.

FOR FURTHER INFORMATION CONTACT: Douglas Anderson, Manager of Aircraft 
Certification and Space Law Branch, Office of the Chief Counsel, 
Federal Aviation Administration, 800 Independence Avenue SW., 
Washington, DC 20591; telephone: 202-267-3073.

SUPPLEMENTARY INFORMATION: 

The Request

    This legal interpretation addresses several regulations in Title 14 
of the Code of Federal Regulation (14 CFR) part 39 applicable to 
airworthiness directives. It responds to questions asked by the Federal 
Aviation Administration's (FAA) Organization/Procedures Working Group 
of the Airworthiness Directive Implementation Aviation Rulemaking 
Committee (AD ARC). The Working Group (WG) requested the agency to 
interpret several provisions in part 39 to resolve issues that have 
been debated within the WG. These issues partly result from amendments 
made to part 39 in 2002. See Airworthiness Directives, 67 FR 47998 
(Jul. 22, 2002). The WG asked four questions:
    1. What is the extent of an aircraft operator's continuing 
obligation following the issuance of an airworthiness directive (AD)?
    2. What is the extent of an aircraft operator's obligation to 
accomplish actions referenced in an AD beyond those actions necessary 
to resolve the unsafe condition specifically identified in an AD?
    3. What is the meaning of the term ``applicable'' in AD 2007-07-02?
    4. What is the extent of an aircraft operator's responsibilities 
when an AD requires an action that cannot be accomplished on a 
particular aircraft?

The FAA published for public comment a proposed legal interpretation 
answering these questions. Proposed Airworthiness Directive Legal 
Interpretation, 76 FR 20898 (Apr. 14, 2011) (Proposed Legal 
Interpretation).\1\ The FAA received numerous comments expressing 
concern with the FAA's proposed interpretation. Most comments focus on 
the FAA's responses to questions 1 and 4.
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    \1\ In response to several requests, the FAA extended the 
comment period until June 30, 2011. 76 FR 30040 (May 24, 2011).

    As an initial matter, it is important to emphasize that each AD is 
unique, and its terms control. Thus, this legal interpretation only 
addresses the matters raised by the AD ARC and is limited to an 
interpretation of part 39 and general agency policy governing ADs.

Legal Interpretation, Summary of Comments and the FAA's Responses

    Some of the commenters suggested that this interpretation should 
change the existing part 39 regulations or FAA internal procedures with 
respect to how ADs are prepared and issued. The FAA rejects those 
suggestions because a regulation cannot be changed by a legal 
interpretation; rulemaking is the proper method for amending a 
regulation.
    Some of the comments raised policy considerations, which provide 
valuable information to the FAA, but those policy considerations cannot 
change the present wording of the regulations, and are best taken into 
account during rulemaking. A legal interpretation only may explain the 
meaning of the words that are in the existing regulation; it may not 
create new policy. Set forth below is a summary and response to 
comments as to the proper interpretation of existing provisions of part 
39.

Question 1: What is the extent of an aircraft operator's continuing 
obligation following the issuance of an airworthiness directive (AD)?

    Answer: The FAA interprets Sec. Sec.  39.7 and 39.9 to mean that 
operators have an ongoing obligation to ensure that the modification 
mandated by an AD is maintained.
    For changes to AD-mandated modifications and for deviations from 
ADs that do not have a terminating action, the operator must obtain 
approval for an alternative means of compliance (AMOC) with the AD. The 
FAA recognizes that in some cases this may impose a burden on operators 
to obtain AMOC approvals for activities that would otherwise be 
considered normal maintenance. The FAA may allow, on an AD-by-AD basis, 
reversion to part 43 maintenance, with airworthiness limitations if 
appropriate to prevent operators from reintroducing unsafe conditions.

Summary of Comments Received

    Some commenters contended that the words of the regulation must be 
given their plain meaning and that the proposed interpretation is not 
consistent with the regulatory text. Section 39.9 provides, ``If the 
requirements of an airworthiness directive have not been met, you 
violate Sec.  39.7 each time you operate the aircraft or use the 
product.'' Some commenters suggested that this means that once the 
requirements of the AD are met, the action has been taken to resolve 
the unsafe condition and the AD is, therefore, no longer applicable. 
Indeed, some commenters further contended that after the AD's 
requirements have been met, it is likely that the product will be in a 
new type design that is different from the type design covered under 
the AD, and therefore, the product now falls out of the AD's 
applicability. While some commenters contended that Sec.  39.9 contains 
no continuing obligation to maintain an AD-mandated condition, other 
commenters suggested that the standard maintenance practices under 
other parts should then control. A significant number of the comments 
objected to maintaining an AD-mandated configuration in perpetuity 
without any allowance for or consideration of normal maintenance, 
alterations, and design changes properly performed and approved in 
accordance with parts 21 and 43.

FAA's Response to Comments

    Under Sec. Sec.  39.7 and 39.9, operators must comply with the 
requirements of applicable ADs and must operate aircraft in accordance 
with all applicable ADs. Section 39.7 prohibits the operation of a 
product that fails to meet AD requirements. Section 39.9 imposes a 
continuing obligation to maintain compliance with an AD by establishing 
a separate violation for each time an aircraft is operated or a product 
is used that fails to meet AD requirements. When these sections are 
read together in the context of part 39, an AD requires that products 
be operated free of any identified unsafe condition. The FAA issues ADs 
not only to require operators to accomplish particular actions listed 
in the AD, but also to ensure that, when products are operated, they 
are free of identified unsafe conditions. It is important that once the 
unsafe condition is corrected as required by an AD, the unsafe 
condition not be reintroduced. Even if the configuration of the 
airplane has changed to comply with the AD, it does not mean that the 
AD no longer applies.
    There are two main categories of ADs issued by the FAA: (1) Ongoing 
inspection and/or maintenance requirements that address a known unsafe 
condition or an unsafe condition likely to exist; and (2) ADs that 
require modifications, which may be ``terminating actions'' for ongoing 
requirements, and which remove the unsafe condition. Sections 39.7 and 
39.9 impose a continuing obligation to comply with both types of AD 
requirements.
    The comments appear to manifest confusion regarding the second type 
of AD and specifically the use of the term ``terminating action'' in an 
AD. While

[[Page 24695]]

how that term is used in an individual AD controls, general guidance of 
the FAA's general use of such term follows. Terminating action ADs 
allow or direct operators to perform a maintenance action that removes 
the unsafe condition from the affected aircraft and eliminates the need 
for the AD's inspection requirements. One example of a terminating 
action is the removal and replacement of a defective part that had been 
subject to AD-mandated repetitive inspections. After a ``terminating 
action,'' the resulting configuration constitutes an FAA-approved type 
design which must be maintained as required by Sec. Sec.  39.7 and 
39.9. This configuration must also be maintained in order for the 
aircraft to be airworthy.\2\
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    \2\ Any operation of an unairworthy aircraft is subject to 
enforcement action under Part 91.
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    Terminating actions fall into two broad categories--those that 
either (1) correct whatever defect kept the product from conforming to 
an approved type design; or (2) accomplish a required change in type 
design where the FAA has determined that the original type design does 
not comply with the applicable airworthiness standards. In both cases, 
the post-AD configuration meets type certification requirements and 
renders the aircraft in a condition for safe operation. An aircraft 
operator must maintain that resulting configuration, and may not change 
it to any other configuration that does not comply either with the AD 
or with an approved AMOC to the AD.
    For ADs mandating modifications where the AD requires no further 
action after modification, the operator may perform standard 
maintenance practices on that new configuration, associated with 
maintaining the fleet, which would not change the required 
modification, and may do so without AMOC approval. Any change from the 
mandated modification, however, requires FAA approval of an AMOC.\3\
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    \3\ Parts 21 and 43 also prohibit the reintroduction of an 
unsafe condition.
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    When an unsafe condition is eliminated in production before the FAA 
issues the AD, the FAA limits the applicability of the AD requirements 
to exclude those newly produced aircraft. Those new aircraft resolve 
the unsafe condition by having appropriate modifications incorporated 
into their type design during production and initial airworthiness 
certification. Continued compliance with the type design, inspection, 
and maintenance requirements under parts 21 and 43 for that product 
should ensure that operators maintain the product's condition for safe 
operation. In contrast, when the FAA issues an AD, it is because the 
agency determined that regulatory requirements have not effectively 
prevented an unsafe condition of the affected products. Therefore, 
Sec.  39.7 requires that, when a product is operated, it must meet the 
requirements of all applicable ADs including any ongoing mandated 
inspection and maintenance requirements that may override general part 
43 maintenance practices.

Question 2: What is the extent of an aircraft operator's obligation to 
accomplish actions referenced in an AD beyond those actions necessary 
to resolve the unsafe condition specifically identified in an AD?

    Answer: An AD may require more actions than correcting the specific 
unsafe condition. These may include actions reasonably related to 
resolving or preventing the unsafe condition. Thus, an aircraft 
operator has an obligation to accomplish all actions required by an AD 
including those beyond the actions necessary to resolve the unsafe 
condition specifically identified in an AD.

Summary of Comments Received

    Some commenters argued that the FAA's interpretation is not 
consistent with the regulatory text because by its terms Sec.  39.11 is 
limited to actions to resolve only the ``unsafe condition.'' According 
to such commenters, if an action required by the AD does not directly 
affect the unsafe condition, those actions are over-prescriptive and 
outside the scope of the FAA's authority.
    Other commenters take the opposite view. As Airbus, a design 
approval holder (DAH) noted, operators often request complete sets of 
instructions for preparation, procedures, test, and closing up. 
Additionally, DAH-determined tools, methods, proceedings, materials, 
and instructions to be used for accomplishing a service instruction for 
continued airworthiness are part of the type design under Sec.  21.31.

FAA's Response to Comments

    The FAA's interpretation is consistent with Title 49 of United 
States Code, Section 44701, which establishes the FAA's broad authority 
to issue regulations in the interest of aviation safety and the FAA 
issues ADs under such authority. In addition, Sec.  39.11 of the 
regulations provides:

    Sec.  39.11 What actions do airworthiness directives require? 
Airworthiness directives specify inspections you must carry out, 
conditions and limitations you must comply with, and any actions you 
must take to resolve an unsafe condition (emphasis added).

    When describing the types of actions required by an AD, which is a 
final rule, Sec.  39.11 does not limit the agency's broad statutory 
authority. AD requirements are imposed by the language of the AD itself 
and not by Sec.  39.11. Thus, an AD may require more actions than 
simply correcting the specific unsafe condition by, for example, 
requiring certain continuing maintenance actions to prevent or detect 
the unsafe condition in the future.
    In developing an AD, the FAA determines the range of actions that 
are reasonably related to and further the interest of aviation 
safety.\4\ For example, service information frequently includes 
instructions for accessing the area to be worked on to address the 
unsafe condition. Because these access instructions are reasonably 
related to addressing the unsafe condition, the FAA has the authority 
to mandate such instructions by AD.
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    \4\ The FAA has ``broad authority to require whatever types of 
corrective actions we determine to be most effective in addressing 
identified unsafe conditions. This includes inspections, repairs, 
modifications, operating limitations, airworthiness limitations, and 
maintenance program requirements.'' Airworthiness Directives, 67 FR 
47998-01 (Jul. 22, 2002). The FAA issues ADs under the 
Administrative Procedure Act (APA); therefore, if the actions 
required by an AD are reasonably related to resolution of the unsafe 
condition, the FAA may mandate them. 5 U.S.C.A. Sec.  551 et seq.
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    The rulemaking process by which individual ADs are adopted provides 
the public with an opportunity to identify and express concern with 
potentially overly prescriptive requirements. In addition, each AD 
contains a provision allowing for approval of an AMOC, which allows an 
operator to address an unsafe condition in a manner approved by the 
FAA.

Question 3: What is the meaning of the term ``applicable'' in AD 2007-
07-02? \5\
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    \5\ AD 2007-07-02 paragraph (f) states in pertinent part that 
operators must ``do[] all the applicable actions specified in the 
Accomplishment Instructions of the applicable service bulletin 
specified in Table 1 of this AD.''.
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    Answer: The FAA interprets ``applicable'' to limit the required 
actions to those that apply to a particular aircraft under the specific 
conditions found. The use of ``applicable'' does not permit an operator 
to decide which actions are necessary to correct the unsafe condition.

Summary of Comments Received

    One commenter contended there was no ambiguity in the subject AD 
because

[[Page 24696]]

the SB specifically list the fleets affected, and which steps are 
applicable based on several different configurations of various 
aircraft. Therefore, the commenter concluded there is no need to 
include the word ``applicable'' to exclude those products for which the 
requirements clearly do not apply.
    ARSA commented that under part 39 the FAA cannot make anything 
``applicable'' that is not directly related to the unsafe condition and 
specified actions must be limited to those that directly address the 
unsafe condition. In its view, the FAA's interpretation mandates 
accomplishing all actions, whether or not necessary to correcting the 
unsafe condition, which is contrary to part 39.

FAA's Response to Comments

    The FAA intends ``applicable'' to have the same meaning in both 
places in paragraph (f) of AD 2007-07-02. The first usage limits the 
required actions to those that apply to a particular aircraft under the 
specific conditions found; it does not permit an operator to decide 
which actions are necessary and which are unnecessary to correct the 
unsafe condition.
    The second usage references Table 1 in the AD that identifies the 
model of aircraft to which each service bulletin applies. The 
``applicable service bulletin'' means the service bulletin that applies 
to each corresponding aircraft model, as indicated in Table 1 of the 
AD. Similarly, ``all the applicable actions'' specified in each 
applicable service bulletin are those actions that are identified as 
applying to a particular aircraft. ``Applicable'' is a necessary 
qualifier in this context for two reasons: (1) In many ADs, the 
referenced service bulletins specify different actions for different 
aircraft configurations, typically identified as ``Group 1,'' ``Group 
2,'' etc.; (2) in many ADs, the referenced service bulletins specify 
different actions depending on conditions found during performance of 
previous steps in the instructions (e.g., if a crack is smaller than a 
specified size, repair in accordance with the Structural Repair Manual; 
if larger, repair in accordance with a method approved by the Aircraft 
Certification Office). The term ``applicable'' limits the AD's 
requirements to only those that are specified in the service bulletin 
for the configuration and conditions of a particular aircraft. In this 
case, the word ``all'' means that every applicable action must be 
accomplished.
    Although this response applies specifically to AD 2007-07-02, this 
general principle also applies to uses of the term ``applicable'' in 
other ADs. The FAA promulgates ADs with specific standards to directly 
address the identified unsafe condition. As exemplified by AD 2007-07-
02, ADs often require many different actions for various models and 
aircraft configurations. Because of those complexities, mandating AD 
actions without incorporating by reference the manufacturer's service 
bulletin that may contain ``normal'' part 43 maintenance actions 
becomes impracticable or may interject unnecessary complexities or 
inconsistencies that adversely affect performance of the necessary 
corrective actions.

Question 4: What is the extent of an aircraft operator's 
responsibilities when an AD requires an action that cannot be 
accomplished on a particular aircraft?

    Answer: Sections 39.15 and 39.17 require ADs to apply to a specific 
product, even if the product has been changed through component removal 
or replacement or other modification. An operator who cannot comply 
with the specific requirements of an AD must request approval of an 
AMOC from the FAA. The operator must obtain an AMOC approval even if 
the affected component has been removed from the aircraft, rendering 
compliance with the specific requirements of the AD impossible. The 
AMOC process allows the FAA to determine whether the unsafe condition 
has been eliminated when an operator removes a component addressed in 
an AD and replaces it with a different component.

Summary of Comments

    Some commenters stated the FAA's interpretation is either wrong 
because when the AD pertains to a specific part or component that has 
since been legally removed or pertains to a part or such that is not 
installed on the aircraft, the AD no longer applies, or represents a 
change from past practice or guidance.

FAA Response to Comments

    If a change to a product makes it impossible to comply with the 
requirements of an AD, then the operator must request an AMOC approval 
from the FAA. Sections 39.15 and 39.17 directly answer this issue. 
Section 39.15 provides that an AD applies to each product identified in 
the AD, even if an individual product has been changed by modifying, 
altering, or repairing it in the area addressed by the AD. Section 
39.17 requires that if a change in a product affects an operator's 
ability to accomplish the actions required by the AD in any way, the 
operator must request FAA approval of an AMOC. Together these sections 
require an operator who cannot comply with the specific requirements of 
an AD to request FAA approval of an AMOC. The operator must obtain an 
AMOC approval even if the affected product has been removed from the 
aircraft, rendering compliance with the specific requirements of the AD 
impossible. The AMOC process allows the FAA to determine whether the 
unsafe condition has been eliminated when an operator removes a 
component to which an AD applies and replaces it with a different 
component.
    This approach was clearly specified in the FAA's part 39 rulemaking 
in 2002. See Airworthiness Directives, 67 FR 47998 (``Specifically, FAA 
is adding to part 39 the language explaining that ADs apply even if 
products have been modified, altered, or repaired in the area addressed 
by the directive.''). The 2002 rulemaking did not introduce any new 
regulatory requirements; rather, the FAA simply codified in part 39 
provisions currently found in ADs. Id. at 47999. If a change in a 
product affects one's ability to comply with the AD, the person 
operating the aircraft or using the product must ask the FAA's 
permission to use an AMOC, and the request must either show that the 
change eliminated the unsafe condition or include the specific actions 
proposed. Id. at 48000.
    This response was coordinated with the Aircraft Maintenance 
Division of the Flight Standards Service and the Design, Manufacturing 
and Airworthiness Division of the Aircraft Certification Service.

    Issued in Washington, DC, on April 19, 2016.
Lorelei Peter,
Assistant Chief Counsel for Regulations.
[FR Doc. 2016-09667 Filed 4-26-16; 8:45 am]
 BILLING CODE 4910-13-P