[Federal Register Volume 67, Number 136 (Tuesday, July 16, 2002)]
[Rules and Regulations]
[Pages 46580-46581]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-17548]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-127-AD; Amendment 39-12820; AD 2002-14-20]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, -800, and -
900 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain Boeing Model 737-600, -700, -800, and -900 
series airplanes. This action requires measuring the electrical voltage 
at the circuit breaker for a certain pitot heater to determine if the 
pitot heater is connected to the correct power supply bus, and 
performing corrective action, if necessary. This action is necessary to 
prevent ice from blocking the pitot tube that provides airspeed data to 
the captain. Such ice blockage could lead to the flightcrew receiving 
incorrect airspeed data, which could result in loss of control of the 
airplane if the flightcrew fails to recognize that the data are 
incorrect. This action is intended to address the identified unsafe 
condition.

DATES: Effective July 31, 2002.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of July 31, 2002.
    Comments for inclusion in the Rules Docket must be received on or 
before September 16, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2002-NM-127-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: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2002-NM-127-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 this AD 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; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Technical Information: Binh Tran, 
Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2890; fax (425) 227-1181.
    Other Information: Judy Golder, Airworthiness Directive Technical 
Editor/Writer; telephone (425) 687-4241, fax (425) 227-1232. Questions 
or comments may also be sent via the Internet using the following 
address: [email protected]. Questions or comments sent via the 
Internet as attached electronic files must be formatted in Microsoft 
Word 97 for Windows or ASCII text.

SUPPLEMENTARY INFORMATION: The FAA has received reports indicating 
that, on certain Boeing Model 737-600, -700, -800, and -900 series 
airplanes, the captain's indicated airspeed sensor and the captain's 
display unit may give inconsistent airspeed data to the flightcrew. 
Investigation of two incidents has revealed that, during production, 
the circuit breaker wire for the captain's pitot heater was connected 
to the 28-volt alternating current (AC) power supply bus, instead of 
the 115-volt AC standby power supply bus. The 28-volt power supply bus 
does not supply sufficient electrical power to heat the captain's pitot 
probe and keep it free of ice. This condition, if not corrected, could 
cause ice blockage of the captain's pitot probe, leading to the 
flightcrew receiving incorrect airspeed data, which could result in 
loss of control of the airplane if the flightcrew fails to recognize 
that the data are incorrect.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
737-24A1150, dated April 11, 2002, which describes procedures for 
measuring the electrical voltage at the circuit breaker for the 
captain's pitot heater to determine if the pitot heater is connected to 
the correct power supply bus, and performing corrective action, if 
necessary. The corrective action involves connecting the subject 
circuit breaker wire to the 115-volt AC standby power supply bus, 
performing a test to ensure that the pitot heater system operates 
correctly, and repeating the measurement of the electrical voltage at 
the circuit breaker for the captain's pitot heater. If the test fails 
or the electrical voltage is still incorrect, the service bulletin 
specifies to troubleshoot the problem and repeat the corrective 
actions. Accomplishment of the actions specified in the service 
bulletin is intended to adequately address the identified unsafe 
condition.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, this AD is 
being issued to prevent ice from blocking the pitot tube that provides 
airspeed data to the captain, which could lead to the flightcrew 
receiving incorrect airspeed data and result in loss of control of the 
airplane if the flightcrew fails to recognize that the data are 
incorrect. This AD requires accomplishment of the actions specified in 
the service bulletin described previously, except as discussed below.

Difference Between Service Information and This AD

    While the service bulletin specifies that no further action is 
necessary if the voltage measurement of the circuit breaker for the 
captain's pitot heater is 115 volts AC, paragraph (a)(1) of this AD 
states that, if the measurement is between 100 and 122 volts AC, no 
further action is required by this AD. The range of 100 to 122 volts AC 
specified in this AD accounts for normal variances that may be 
encountered during the voltage measurement.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire.

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Communications shall identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Submit comments using the following format:
     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.
     For each issue, state what specific change to the AD is 
being requested.
     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 rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2002-NM-127-AD.'' The postcard will be date stamped 
and returned to the commenter.

Regulatory Impact

    The regulations adopted herein 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket.
    A copy of it, if filed, 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, Incorporation by 
reference, 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), 40113, 44701.


Sec. 39.13  [Amended]

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

2002-14-20  Boeing: Amendment 39-12820. Docket 2002-NM-1AD.

    Applicability: Model 737-600, -700, -800, and -900 series 
airplanes; as listed in Boeing Alert Service Bulletin 737-24A1150, 
dated April 11, 2002; 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 ice from blocking the pitot tube that provides 
airspeed data to the flightcrew, which could lead to the flightcrew 
receiving incorrect airspeed data, and result in loss of control of 
the airplane if the flightcrew fails to recognize that the data are 
incorrect, accomplish the following:

Measurement of Voltage and Corrective Actions

    (a) Within 60 days after the effective date of this AD, measure 
the electrical voltage at the circuit breaker for the captain's 
pitot heater to determine if the pitot heater is connected to the 
correct power supply bus, per Boeing Alert Service Bulletin 737-
24A1150, dated April 11, 2002.
    (1) If the measurement is 100 to 122 volts alternating current 
(AC): No further action is required by this AD.
    (2) If the measurement is not 100 to 122 volts AC: Before 
further flight, perform all actions associated with connecting the 
subject circuit breaker wire to the 115-volt AC standby power supply 
bus (including performing a test to ensure that the pitot heater 
system operates correctly, repeating the measurement of the 
electrical voltage at the circuit breaker for the captain's pitot 
heater, and troubleshooting and correcting the wire connections 
until the test and measurement are successful), per the service 
bulletin.

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 2: 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.

Incorporation by Reference

    (d) The actions shall be done in accordance with Boeing Alert 
Service Bulletin 737-24A1150, dated April 11, 2002. This 
incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. Copies may be obtained from Boeing Commercial Airplane Group, 
P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be 
inspected at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Effective Date

    (e) This amendment becomes effective on July 31, 2002.

    Issued in Renton, Washington, on July 8, 2002.
Vi Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-17548 Filed 7-15-02; 8:45 am]
BILLING CODE 4910-13-P