[Federal Register Volume 66, Number 35 (Wednesday, February 21, 2001)]
[Proposed Rules]
[Pages 10972-10974]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-4220]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-320-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-400 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 747-400 
series airplanes. This proposal would require an inspection to detect 
miswiring of diodes in the heating system of the pitot static probes, 
and corrective action, if necessary. This action is necessary to 
prevent reduced power to the heating system of the pitot static probes, 
leading to ice accumulation on the pitot static probes, which could 
result in erroneous airspeed or altitude indications to the flight 
crew, and consequent reduced operational safety in all phases of 
flight. This action is intended to address the identified unsafe 
condition.

DATES: Comments must be received by April 9, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-320-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
<a href="/cdn-cgi/l/email-protection#41786c202f2c6c2f31332c222e2c2c242f35012720206f262e37"><span class="__cf_email__" data-cfemail="e1d8cc808f8ccc8f91938c828e8c8c848f95a1878080cf868e97">[email protected]</span></a>. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-320-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Don Eiford, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056; telephone (425) 227-2788; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained

[[Page 10973]]

in this action may be changed in light of the comments received.
    Submit comments using the following format:
    <bullet> Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
    <bullet> For each issue, state what specific change to the proposed 
AD is being requested.
    <bullet> Include justification (e.g., reasons or data) for each 
request.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NM-320-AD.'' The postcard will be date stamped 
and returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 2000-NM-320-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that several operators have 
found burnt diodes in the heating system of the pitot static probes on 
certain Boeing Model 747-400 series airplanes. Investigation revealed 
that diodes in the power reduction circuitry were miswired. The 
miswiring results in the probe-head heat element always being at full-
power, while the probe strut heater is only at half-power. If the probe 
strut heater is only at half-power, ice may accumulate on the pitot 
static probes. This condition, if not corrected, could result in 
erroneous airspeed or altitude indications to the flight crew, and 
consequent reduced operational safety in all phases of flight.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-30A2078, Revision 1, dated November 16, 2000, which describes 
procedures for an inspection to detect miswiring of diodes in the 
heating system of the pitot probes. The inspection involves using a 
multimeter to verify continuity between certain relay sockets, absence 
of a diode between certain relay sockets, and diode orientation between 
certain relay sockets. If any miswiring is found, the service bulletin 
specifies to rewire per Boeing 747-400 Wiring Diagrams 30-31-11 and 30-
31-21. Doing the actions in the service bulletin is intended to 
adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require operators to do the actions specified in the 
service bulletin described previously, except as discussed below.

Differences Between This Proposed AD and the Service Bulletin

    Operators should note that, although the service bulletin 
recommends accomplishing the inspection at the earliest maintenance 
opportunity when manpower and facilities are available, the FAA has 
determined that this compliance time may not ensure that the identified 
unsafe condition is addressed in a timely manner. In developing an 
appropriate compliance time for this proposed AD, the FAA considered 
not only the manufacturer's recommendation, but the degree of urgency 
associated with addressing the subject unsafe condition, the average 
utilization of the affected fleet, and the time necessary to perform 
the proposed AD. In light of all of these factors, the FAA finds a 15-
month compliance time to be warranted, in that it represents an 
appropriate interval of time allowable for affected airplanes to 
continue to operate without compromising safety.
    Operators also should note that, while the service bulletin 
describes only an inspection/verification that necessitates use of a 
multimeter, this proposed AD refers to this inspection/verification as 
a ``special detailed inspection.'' The definition of a ``special 
detailed inspection'' is included as a note in the proposed AD.

Cost Impact

    There are approximately 497 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 69 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
2 work hours per airplane to accomplish the proposed actions, and that 
the average labor rate is $60 per work hour. Based on these figures, 
the cost impact of the proposed AD on U.S. operators is estimated to be 
$8,280, or $120 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed requirements of 
this AD action, and that no operator would accomplish those actions in 
the future if this proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect on the States, on the relationship between the national 
Government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting 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.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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:


[[Page 10974]]


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


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Boeing: Docket 2000-NM-320-AD.

    Applicability: Model 747-400 series airplanes, as listed in 
Boeing Alert Service Bulletin 747-30A2078, Revision 1, dated 
November 16, 2000; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (b) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent reduced power to the heating system of the pitot 
static probes, leading to ice accumulation on the pitot static 
probes, which could result in erroneous airspeed or altitude 
indications to the flight crew, and consequent reduced operational 
safety in all phases of flight, accomplish the following:

Inspection

    (a) Within 15 months after the effective date of this AD, 
perform a special detailed inspection to detect miswiring of diodes 
in the heating system of the pitot static probes by using a 
multimeter to verify continuity between certain relay sockets, 
absence of a diode between certain relay sockets, and diode 
orientation between certain relay sockets, per Boeing Alert Service 
Bulletin 747-30A2078, Revision 1, dated November 16, 2000. If any 
miswiring is found, rewire per Boeing 747-400 Wiring Diagrams 30-31-
11 and 30-31-21, as referenced in the service bulletin.

    Note 2: Inspections accomplished prior to the effective date of 
this AD per Boeing Alert Service Bulletin 747-30A2078, dated August 
24, 2000, are considered acceptable for compliance with the 
applicable action specified in this amendment.


    Note 3: For the purposes of this AD, a special detailed 
inspection is defined as: ``An intensive examination of a specific 
item(s), installation, or assembly to detect damage, failure, or 
irregularity. The examination is likely to make extensive use of 
specialized inspection techniques and/or equipment. Intricate 
cleaning and substantial access or disassembly procedures may be 
required.''

Alternative Methods of Compliance

    (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. 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 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (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.

    Issued in Renton, Washington, on February 13, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-4220 Filed 2-20-01; 8:45 am]
BILLING CODE 4910-13-U


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