[Federal Register Volume 66, Number 92 (Friday, May 11, 2001)]
[Rules and Regulations]
[Pages 24049-24051]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-11899]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-123-AD; Amendment 39-12226; AD 2001-10-01]
RIN 2120-AA64


Airworthiness Directives; Empresa Brasileira de Aeronautica S.A. 
(EMBRAER) Model EMB-135 and EMB-145 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 Empresa Brasileira de Aeronautica S.A. 
(EMBRAER) Model EMB-135 and EMB-145 series airplanes. This action 
requires revising the FAA-approved Airplane Flight

[[Page 24050]]

Manual to prohibit in-flight auxiliary power unit (APU) starts, and 
installing a placard on or near the APU start/stop switch panel to 
provide such instructions to the flight crew. This action is necessary 
to prevent flame backflow into the APU compartment through the eductor 
during in-flight APU starts, which could result in fire in the APU 
compartment. This action is intended to address the identified unsafe 
condition.

DATES: Effective May 29, 2001.
    Comments for inclusion in the Rules Docket must be received on or 
before June 11, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-123-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 the Internet must contain 
``Docket No. 2001-NM-123-AD'' in the subject line and need not be 
submitted in triplicate. Comments sent via fax or the Internet as 
attached electronic files must be formatted in Microsoft Word 97 for 
Windows or ASCII text.
    Information pertaining to this amendment may be examined at the 
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the FAA, Atlanta Aircraft Certification Office, One 
Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia.

FOR FURTHER INFORMATION CONTACT: Linda M. Haynes, Aerospace Engineer, 
Airframe and Propulsion Branch, 
ACE-117A, FAA, Atlanta Aircraft Certification Office, One Crown Center, 
1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30337-2748; 
telephone (770) 703-6091; fax (770) 703-6097.

SUPPLEMENTARY INFORMATION: The Departmento de Aviacao Civil (DAC), 
which is the airworthiness authority for Brazil, recently notified the 
FAA that an unsafe condition may exist on certain EMBRAER Model 
EMB-135 and EMB-145 series airplanes. The DAC advises that it has 
received a report of occurrences of auxiliary power unit (APU) flame 
backflow into the APU compartment through the exhaust eductor, during 
in-flight APU starts.
    The airplane manufacturer (EMBRAER) has reported to the DAC and FAA 
that two APU fire alarms were triggered during in-flight APU starts at 
30,000 feet on two airplanes. As a result, the fire sensors were 
replaced, but the same event occurred again in one of the airplanes. 
EMBRAER then inspected all APU's on the production fleet at its 
manufacturing facility, and found evidence of flame backflow (flames 
ingested back into the APU compartment) and minor damage (singed 
harness ties and discoloration) on four airplanes.
    EMBRAER and Hamilton Sunstrand Power Systems (the APU manufacturer) 
further investigated the APU flame backflow events to determine the 
cause. Based on theoretical analysis and field data, the two 
manufacturers reached the following conclusions:
     The root cause is due to flames (that were generated 
during in-flight APU starts) being ingested into the APU compartment 
through the eductor.
     The event is only possible during in-flight APU start 
attempts at high altitudes where the fuel mixture tends to be rich. In 
that case, torching flames can occur when excessive fuel exits the 
combustor and is burned in the exhaust as the new air mixes with the 
hot gases.
     For APU ground starts only, none of the EMBRAER production 
airplanes showed burn marks. When the APU was used on approach for 
landing at lower altitudes (5,000 to 10,000 feet), field inspections of 
all affected airplanes (five airplanes with the APU model specified in 
the applicability of this AD) showed no burn marks.
     The probability of having a flame backflow event increases 
during high speeds. The APU manufacturer has found that if a large 
amount of pressure is present on the exhaust, the compressor may not 
have enough efficiency to overcome this pressure during the first 
stages of an in-flight APU start. In this case, the flame backflow 
would be diverted into the tailcone.
    Even though there have been no occurrences of this flame backflow 
event at low altitudes, the DAC and FAA have determined that it is 
still possible for the flame backflow to occur. For that reason, both 
the DAC and FAA consider that any inflight starts of the APU could 
adversely affect the safety of flight.

Explanation of Relevant Foreign Airworthiness Information

    The DAC issued Brazilian emergency airworthiness directive 2001-04-
02, dated April 12, 2001, in order to assure the continued 
airworthiness of these airplanes in Brazil. The Brazilian airworthiness 
directive references procedures for installing the APU placard in 
EMBRAER Alert Service Bulletin 145-49-A017, dated April 12, 2001.

FAA's Conclusions

    These airplane models are manufactured in Brazil and are type 
certificated for operation in the United States under the provisions of 
Sec. 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the 
applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, the DAC has kept the FAA informed of 
the situation described above. The FAA has examined the findings of the 
DAC, reviewed all available information, and determined that AD action 
is necessary for products of this type design that are certificated for 
operation in the United States.

Explanation of Requirements of Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, this AD is being issued to prevent flame backflow 
into the APU compartment through the eductor during in-flight APU 
starts, which could result in fire in the APU compartment. This AD 
requires revising the 
FAA-approved Airplane Flight Manual to prohibit in-flight APU starts, 
and installing a placard on or near the APU start/stop switch panel to 
provide such instructions to the flight crew.

Differences Between the Brazilian Airworthiness Directive and This 
AD

    Operators should note that the service bulletin referenced in the 
Brazilian airworthiness directive specifies installing the decal 
(placard) in the ``pedestal panel'' of the airplane, and the Brazilian 
airworthiness directive specifies such installation in the ``main 
instrument panel.'' However, paragraph (b) of this AD specifies 
installing the placard ``on or near the APU start/stop switch panel.''

Interim Action

    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.

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.

[[Page 24051]]

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. 
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 2001-NM-123-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, 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:

2001-10-01  Empresa Brasileira de Aeronautica S.A. (EMBRAER): 
Amendment 39-12226. Docket 2001-NM-123-AD.

    Applicability: Model EMB-135 and EMB-145 series airplanes, 
certificated in any category, equipped with Hamilton Sundstrand 
Power Systems auxiliary power unit (APU) model T-62T-40C14 (APS 
500R).
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent flame backflow into the APU compartment through the 
eductor during in-flight APU starts, which could result in fire in 
the APU compartment, accomplish the following:

Airplane Flight Manual (AFM) Revision

    (a) Within 25 flight hours or 10 days after the effective date 
of this AD, whichever occurs first, accomplish the actions required 
by paragraphs (a)(1) and (a)(2) of this AD.
    (1) Install a placard on or near the APU start/stop switch panel 
that reads:

``Caution: In-Flight APU Starts are Prohibited''

    (2) Revise the Limitations Section of the FAA-approved AFM to 
include the information on the placard, as specified in paragraph 
(a)(1) of this AD, and to limit APU starts to ground conditions 
only. This may be accomplished by inserting a copy of this AD in the 
AFM.

    Note 1: Because APU starts are prohibited in flight when an 
engine-driven generator is inoperative, the APU must be started on 
the ground in order to dispatch, and the APU must be kept 
operational for the entire flight.

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, Atlanta 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, Atlanta ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Atlanta ACO.

Special Flight Permits

    (c) Special flight permits may be issued in accordance with 
Secs. 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.

    Note 3: The subject of this AD is addressed in Brazilian 
emergency airworthiness directive 2001-04-02, dated April 12, 2001.

Effective Date

    (d) This amendment becomes effective on May 29, 2001.

    Issued in Renton, Washington, on May 7, 2001.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate,Aircraft Certification 
Service.
[FR Doc. 01-11899 Filed 5-10-01; 8:45 am]
BILLING CODE 4910-13-U