[Federal Register Volume 69, Number 80 (Monday, April 26, 2004)]
[Proposed Rules]
[Pages 22461-22463]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-9382]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-297-AD]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model DHC-8-301, -311, and -
315 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 Bombardier Model DHC-8-
301, -311, and -315 airplanes. This proposal would require determining 
the modification number of the angle of attack (AOA) sensor vanes; 
testing the movement of the affected vanes to evaluate sticking against 
both the upper and the lower vane travel end stops; and corrective 
action, if necessary. This action is necessary to prevent an incorrect 
AOA indication to the stall warning system in flight, which could 
result in an inadvertent stall and consequent loss of control of the 
airplane. This action is intended to address the identified unsafe 
condition.

DATES: Comments must be received by May 26, 2004.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2002-NM-297-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 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-297-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 or 2000 or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Bombardier, Inc., Bombardier Regional Aircraft Division, 
123 Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. This 
information may be examined at the FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington; or at the FAA, New York 
Aircraft Certification Office, 1600 Stewart Avenue, Westbury, New York.

FOR FURTHER INFORMATION CONTACT: Ezra Sasson, Aerospace Engineer, 
Systems and Flight Test Branch, ANE-172, New York Aircraft 
Certification Office, FAA, 1600 Stewart Avenue, suite 410, Westbury, 
New York 11590; telephone (516) 228-7320; fax (516) 794-5531.

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 in this action may be changed in 
light of the comments received.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, 
discuss a request to

[[Page 22462]]

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 proposed 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 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 2002-NM-297-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. 2002-NM-297-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    Transport Canada Civil Aviation (TCCA), which is the airworthiness 
authority for Canada, notified the FAA that an unsafe condition may 
exist on certain Bombardier Model DHC-8-301, -311, and -315 airplanes. 
TCCA advises that the manufacturer of the angle of attack (AOA) sensor 
vane has determined that a damper within the AOA sensor in some vanes 
can leak oil. Such leakage could cause the vane to stick against the 
upper or the lower travel end stop. Although no problems with sticking 
AOA vanes have been reported on the subject airplanes, other airplanes 
using similar sensor designs have experienced AOA split indications 
during takeoff roll, which resulted in rejected takeoffs. A sticking 
vane would provide the stall warning system with an incorrect AOA 
reading at airspeeds below approximately 100 knots; above airspeeds of 
110 knots, the airflow would release a stuck vane. This condition, if 
not corrected, could result in an incorrect AOA indication to the stall 
warning system in flight, which could cause an inadvertent stall and 
consequent loss of control of the airplane.

Explanation of Relevant Service Information

    Bombardier has issued Alert Service Bulletin A8-27-94, Revision 
``A'', dated February 5, 2002, which describes procedures for an 
initial movement test of the AOA sensor vane to evaluate sticking 
against both the upper and the lower vane travel end stops. The service 
bulletin also includes procedures for related investigative and 
corrective actions.
    The initial movement test includes placing a gram gauge 
(dynamometer) against the AOA sensor vane, and recording the gauge 
reading as the vane is moved away from both the upper and the lower 
travel end stops. The related investigative action is repeating the 
movement test one time for sensor vanes that have measurements of less 
than 110 grams.
    The related corrective action is replacing any AOA sensor vane if 
any movement shows certain gram gauge readings from either the upper or 
lower position. If the gram gauge reading is between 110 and 170 grams, 
the service bulletin recommends replacing the AOA sensor vane within 
six months or 1,000 flight hours, whichever occurs first. If a gram 
gauge reading is 170 grams or more, the service bulletin recommends 
replacing the AOA sensor vane within 5 calendar days. The service 
bulletin specifies that only post-MOD ``J'' sensors be used for 
replacement.
    Accomplishment of the actions specified in the service bulletin is 
intended to adequately address the identified unsafe condition.
    TCCA classified this service bulletin as mandatory and issued 
Canadian airworthiness directive CF-2001-46, dated December 3, 2001, to 
ensure the continued airworthiness of these airplanes in Canada.
    Bombardier Alert Service Bulletin A8-27-94, Revision ``A'', dated 
February 5, 2002, references Rosemount Aerospace Alert Service Bulletin 
0861CAB-27A-07, dated September 28, 2001, as an additional source of 
service information for doing the vane movement test of the AOA 
sensors. The Rosemount service bulletin is included in the Bombardier 
service bulletin. This service bulletin also includes procedures for 
sending reports of test findings to Rosemount Aerospace, and for 
sending removed sensors to Rosemount Aerospace for modification.

FAA's Conclusions

    This airplane model is manufactured in Canada and is type 
certificated for operation in the United States under the provisions of 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, TCCA has kept the FAA informed of 
the situation described above. The FAA has examined the findings of 
TCCA, 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 Proposed 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, the proposed AD would require accomplishment of 
the actions specified in the service bulletin described previously, 
except as discussed below.

Differences Among the Proposed AD, Service Bulletins, and the Canadian 
Airworthiness Directive

    The Rosemount Aerospace service bulletin (which is included in the 
Bombardier service bulletin) contains procedures for sending reports of 
test findings to Rosemount, and for sending removed sensors to 
Rosemount for modification. This proposed AD would not include those 
requirements.
    Both the Bombardier service bulletin and the Canadian airworthiness 
directive have a compliance time for the initial movement test, and for 
replacement of certain sensor vanes of 1,000 flight hours or 6 months, 
whichever occurs first. This proposed AD would require that operators 
perform the initial test within 1,000 flight hours or 18 months after 
the effective date of this proposed AD, whichever occurs first; and the 
replacement within 1,000 flight hours or 18 months, whichever occurs 
first, after accomplishing the movement test in which certain 
measurements are found. We find that this compliance time represents an 
appropriate interval for affected airplanes to continue to operate 
without compromising safety. This difference has been coordinated with 
TCCA.

Cost Impact

    The FAA estimates that 57 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 1 work 
hour per airplane to accomplish the proposed inspection to determine 
the modification letter, and that the average labor rate is $65 per 
work hour. Based on these figures, the cost impact of the proposed AD 
on U.S.

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operators is estimated to be $3,705, or $65 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 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:

    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:

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket 2002-NM-297-
AD.

    Applicability: Model DHC-8-301, -311, and -315 airplanes, serial 
numbers 100 through 583, inclusive; certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent an incorrect angle of attack (AOA) indication to the 
stall warning system in flight, which could result in an inadvertent 
stall and consequent loss of control of the airplane, accomplish the 
following:

Service Bulletin References

    (a) The term ``service bulletin,'' as used in this AD, means the 
Accomplishment Instructions of Bombardier Alert Service Bulletin A8-
27-94, Revision ``A'', dated February 5, 2002.

    Note 1: Bombardier Alert Service Bulletin A8-27-94 references 
Rosemount Aerospace Alert Service Bulletin 0861CAB-27A-07, dated 
September 28, 2001, as an additional source of service information 
for testing the AOA sensors. The Rosemount service bulletin is 
included with the Bombardier service bulletin.

Inspection To Determine Modification

    (b) Within 1,000 flight hours or 18 months after the effective 
date of this AD, whichever occurs first, inspect the right and left 
AOA sensor vanes to determine whether modification (MOD) ``J'' has 
been incorporated. Instead of inspecting the sensors, a review of 
airplane maintenance records is acceptable if the MOD level of the 
sensor can be positively determined from that review. If MOD ``J'' 
has been incorporated in both sensors, no further action is required 
by this paragraph.

Movement Tests

    (c) For any AOA sensor vane that does not have MOD ``J'' 
installed: Prior to further flight following the inspection required 
by paragraph (b) of this AD, do a movement test of the AOA sensor 
vane per the service bulletin.
    (d) If the result of the movement test in paragraph (c) of this 
AD is less than 110 grams, repeat the movement test prior to the 
accumulation of 5,000 flight hours or 24 months after accomplishing 
the initial test, whichever occurs first. Do the test per the 
service bulletin.

Corrective Action

    (e) If the result of any movement test in paragraph (c) or 
paragraph (d) of this AD is 110 grams or more, replace the AOA 
sensor vane with a reworked MOD ``J'' sensor vane, per the service 
bulletin, at the applicable time in paragraph (e)(1), (e)(2), or 
(e)(3) of this AD.
    (1) If the result of the movement test in paragraph (c) of this 
AD is between 110 and 169 grams inclusive, replace the sensor vane 
at the earlier of 1,000 flight hours, or 18 months after 
accomplishing the movement test in paragraph (c) of this AD.
    (2) If the result of any repeat movement test in paragraph (d) 
of this AD is between 110 and 169 grams inclusive, replace the 
sensor vane at the earlier of 1,000 flight hours or 6 months after 
accomplishing the movement test in paragraph (d) of this AD.
    (3) If the result of the movement test is 170 grams or more, 
replace the sensor vane within 5 days after accomplishing the 
movement test in paragraph (c) or paragraph (d) of this AD.

Parts Installation

    (f) As of the effective date of this AD, no person may install a 
sensor vane, part number 861CAB, on any airplane unless MOD ``J'' 
has been incorporated.

Reporting and Parts Modification

    (g) Although the Rosemount service bulletin contains procedures 
for sending test findings to the manufacturer, and for sending 
removed parts to the manufacturer for modification, this AD does not 
require those actions.

Actions Accomplished Per Previous Release of Service Bulletin

    (h) Actions accomplished before the effective date of this AD 
per Bombardier Alert Service Bulletin A8-27-94, dated October 25, 
2001, are considered acceptable for compliance with the 
corresponding action specified in this AD.

Alternative Methods of Compliance

    (i) In accordance with 14 CFR 39.19, the Manager, New York 
Aircraft Certification Office, FAA, is authorized to approve 
alternative methods of compliance for this AD.

    Note 2: The subject of this AD is addressed in Canadian 
airworthiness directive CF-2001-46, dated December 3, 2001.


    Issued in Renton, Washington, on April 16, 2004.
Michael J. Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-9382 Filed 4-23-04; 8:45 am]
BILLING CODE 4910-13-P