AD Amdt-39-9430

[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 [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 95-27914]



=======================================================================
-----------------------------------------------------------------------

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.

-----------------------------------------------------------------------

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]
BILLING CODE 4910-13-U