[Federal Register Volume 60, Number 218 (Monday, November 13, 1995)]
[Rules and Regulations]
[Pages 56937-56939]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-27914]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-NM-28-AD; Amendment 39-9430; AD 95-23-10]
Airworthiness Directives; Boeing Model 737 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to all Boeing Model 737 series airplanes, that requires
revising the FAA-approved Airplane Flight Manual (AFM) to provide the
flightcrew with additional procedures for shutting down the auxiliary
power unit (APU) when an APU fire is indicated. This amendment is
prompted by reports indicating that a latent electrical failure exists
in the fire extinguishing system for the APU; this failure could
prevent the APU from shutting down and fire extinguishant from
discharging into the APU compartment in the event of an APU fire. The
actions specified by this AD are intended to ensure that the flightcrew
is provided with procedures for shutting down the APU in the event of
an APU fire.
EFFECTIVE DATE: December 13, 1995.
ADDRESSES: Information pertaining to this rulemaking action may be
examined at the Federal Aviation Administration (FAA), Transport
Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT: Stephen Bray, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate,
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (206) 227-2681; fax (206) 227-1181.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to all Boeing Model 737 series
airplanes was published in the Federal Register on June 2, 1995 (60 FR
28763). That action proposed to require revising the Emergency
Procedures and Limitations Sections of the FAA-approved Airplane Flight
Manual (AFM) to provide the flightcrew with these additional procedures
for shutting down the APU when an APU fire is indicated.
Interested persons have been afforded an opportunity to participate
in the
[[Page 56938]]
making of this amendment. Due consideration has been given to the
comments received.
Three commenters support the proposed rule.
One commenter requests that the requirements of the proposed AD be
made a reference procedure found both in the AFM and the Quick
Reference Handbook, rather than ``recall items'' in the Limitations
section of the AFM. The commenter does not provide justification for
its request. The FAA concurs partially. The FAA finds that the
operational procedure should be included in the Emergency Procedures
Section of the AFM; however, the procedure should not be included in
the Limitations Section. Further, the FAA finds that inclusion of the
procedure in the Quick Reference Handbook, as suggested by the
commenter, will not adequately address the recall requirement of this
AD. The FAA has determined that any hesitation on the part of the
flightcrew with regard to taking action to shut down the APU in the
event of an APU fire could jeopardize safe flight and landing of the
airplane. The FAA finds it critical that the flightcrew commit such
procedures to memory; therefore, these procedures must be considered
recall items. Paragraph (a) of the final rule has been revised to
remove the requirement to include the operational procedure in the
Limitations Section of the AFM.
One commenter agrees that the AFM should be revised to incorporate
the additional procedures specified in the proposed rule. However, the
commenter states that the unsafe condition addressed by the proposal
does not warrant issuance of an AD. The commenter suggests that Boeing
revise the AFM to incorporate the proposed additional procedures, which
would negate the cost of AD compliance paperwork for both the FAA and
operators while providing an equivalent level of safety. The commenter
adds that incorporation of the additional procedures into operators'
manuals (through Boeing issuing a revision to the master AFM) would be
more expeditious than the FAA issuing an AD with a 6-month compliance
period.
The FAA does not concur with the commenter's position that issuance
of an AD is not warranted. As stated in the preamble of the proposed
rule, the FAA received reports indicating that a latent electrical
failure exists in the fire extinguishing system of the APU on the
affected airplanes. This electrical failure presents an unsafe
condition in airplanes, since it could eventually prevent the APU from
shutting down and fire extinguishant from discharging when the flight
crew pulls and rotates the fire handle. Consequently, the flightcrew
would be unable to extinguish an APU fire. The FAA has determined that
this unsafe condition could exist or eventually develop on Model 737
series airplanes, and that revision of the AFM must be mandated to
ensure that safety is not degraded. The appropriate vehicle for
mandating such action to correct an unsafe condition is the
airworthiness directive. However, the FAA has confirmed that Boeing
intends to update the AFM for the affected airplanes in the next
revision, which is scheduled for December 1995.
One commenter, Boeing, requests that the FAA reevaluate the cost-
benefit analysis of the proposed rule. The commenter states that simply
changing the AFM to add a recall item, as proposed in this AD, will not
fully accomplish the intent of the rule; flightcrews must be retrained
to commit the recall item to memory. The commenter states that the cost
benefit analysis should account for such training (including flightcrew
training time, instructors, and updated materials). The commenter
points out that the FAA is required by Executive Order 12866 to do an
analysis to show that benefits outweigh costs before imposing new
regulations. The commenter adds that, in calculating the total cost
impact of the proposed AD, the FAA is stating that industry will be
incurring a cost in implementing this rule that it would otherwise not
be liable for if the rule was not issued.
The FAA acknowledges the concerns of this commenter. The FAA
recognizes that, in accomplishing the requirements of any AD, operators
may incur ``incidental'' costs in addition to the ``direct'' costs that
are reflected in the cost analysis presented in the AD preamble.
However, the cost analysis in AD rulemaking actions typically does not
include incidental costs. In the case of this AD, for example, the
requirements are to revise the AFM to include certain information. How
operators actually ``implement'' that information thereafter (once it
is placed in the AFM) may vary greatly among them: for some operators,
implementation may necessitate extensive retraining among their
flightcrews; for others, implementation may merely be considered a
typical part of the routine, continuous training of their flightcrews.
In light of this, it would be nearly impossible for the FAA to
calculate accurately or to reflect all costs associated with retraining
flightcrews, as suggested by the commenter. (The commenter does not
provide an estimate of such costs.)
Further, because AD's require specific actions to address specific
unsafe conditions, they appear to impose costs that would not otherwise
be borne by operators. However, because of the general obligation of
operators to maintain and operate aircraft in an airworthy condition,
this appearance is deceptive. Attributing those costs solely to the
issuance of this AD is unrealistic because, in the interest of
maintaining and operating safe aircraft, prudent operators would
accomplish the required actions even if they were not required to do so
by the AD. In any case, the FAA has determined that direct and
incidental costs are still outweighed by the safety benefits of the AD.
In addition, the FAA is not required to do a full cost-benefit
analysis for each AD, since an AD typically does not meet the criteria
of a ``significant regulatory action'' under Executive Order 12866. As
a matter of law, in order to be airworthy, an aircraft must conform to
its type design and be in a condition for safe operation. The type
design is approved only after the FAA makes a determination that it
complies with all applicable airworthiness requirements. In adopting
and maintaining those requirements, the FAA has already made the
determination that they establish a level of safety that is cost
beneficial. When the FAA later makes a finding of an unsafe condition
in an aircraft and issues an AD, it means that the original cost
beneficial level of safety is no longer being achieved and that the
required actions are necessary to restore that level of safety. Because
this level of safety has already been determined to be cost beneficial,
and because the AD does not add an additional regulatory requirement
that increases the level of safety beyond what has been established by
the type design, a full cost-benefit analysis for each AD would be
redundant and unnecessary.
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the change previously
described. The FAA has determined that this change will neither
increase the economic burden on any operator nor increase the scope of
the AD.
There are approximately 2,602 Model 737 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 1,072
airplanes of U.S. registry will be affected by this AD, that it will
take approximately 1 work hour per airplane to accomplish the required
[[Page 56939]]
actions, and that the average labor rate is $60 per work hour. Based on
these figures, the cost impact of the AD on U.S. operators is estimated
to be $64,320, or $60 per airplane.
The cost impact figure discussed above is based on assumptions that
no operator has yet accomplished any of the requirements of this AD
action, and that no operator would accomplish those actions in the
future if this AD were not adopted.
The regulations adopted herein will not have substantial direct
effects 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. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this action--(1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979); 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. A final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it may be obtained
from the Rules Docket at the location provided under the caption
ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (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), 40101, 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
95-23-10 Boeing: Amendment 39-9430. Docket 95-NM-28-AD.
Applicability: All Model 737 series airplanes, certificated in
any category.
Compliance: Required as indicated, unless accomplished
previously.
To ensure that the flightcrew is provided with additional
procedures necessary for shutting down the auxiliary power unit
(APU) in the event of an APU fire, accomplish the following:
(a) Within 6 months after the effective date of this AD, revise
the Emergency Procedures Section of the FAA-approved Airplane Flight
Manual (AFM) to include the following procedures, which will ensure
that the flightcrew is able to shut down the APU when an APU fire is
indicated. This may be accomplished by inserting a copy of this AD
in the AFM.
``APU FIRE WARNING
RECALL
APU Fire Warning Switch................... PULL AND ROTATE
APU Switch................................ OFF
REFERENCE
Master Fire Warning....................... RESET''
(b) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Seattle Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Seattle ACO.
Note: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(c) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
(d) This amendment becomes effective on December 13, 1995.
Issued in Renton, Washington, on November 6, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-27914 Filed 11-9-95; 8:45 am]
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