[Federal Register: February 8, 2008 (Volume 73, Number 27)]
[Proposed Rules]
[Page 7494-7498]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr08fe08-19]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 2003-NM-33-AD]
RIN 2120-AA64
Airworthiness Directives; Empresa Brasileira de Aeronautica S.A.
(EMBRAER) Model EMB-120, -120ER, -120FC, -120QC, and -120RT Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Supplemental notice of proposed rulemaking; reopening of
comment period.
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SUMMARY: This document revises an earlier proposed airworthiness
directive (AD), applicable to all EMBRAER Model EMB-120 series
airplanes, that would have required revising the airplane flight manual
to include operational limitations for use of the autopilot, and
installing two placards that advise the flight crew to check the pitch
trim before descent. This new action would retain the original
requirements, but with revised placard language. This new action would
also require modifying the elevator trim system, which would terminate
the requirements of the AD. The actions specified by this new proposed
AD are intended to prevent pitch trim upsets if the pitch trim
actuators jam or freeze, which could result in reduced controllability
of the airplane. This action is intended to address the identified
unsafe condition.
DATES: Comments must be received by March 4, 2008.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 2003-NM-33-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98057-3356. 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:
9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must
contain ``Docket No. 2003-NM-33-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 Empresa Brasileira de Aeronautica S.A. (EMBRAER), P.O.
Box 343--CEP 12.225, Sao Jose dos Campos--SP, Brazil. This information
may be examined at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: Dan Rodina, Aerospace Engineer,
International Branch, ANM-116, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425)
227-2125; fax (425) 227-1149.
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 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 2003-NM-33-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. 2003-NM-33-AD, 1601 Lind Avenue SW., Renton, Washington
98057-3356.
Discussion
A proposal to amend part 39 of the Federal Aviation Regulations (14
CFR part 39) to add an airworthiness directive (AD), applicable to all
EMBRAER Model EMB-120 series airplanes, was published as a notice of
proposed rulemaking (NPRM) in the Federal Register on April 1, 2003 (68
FR 15684). That NPRM would have required revising the airplane flight
manual to include operational limitations for use of the autopilot, and
installing two placards that advise the flight crew to check the pitch
trim before descent. That NPRM was prompted by pitch trim upsets during
the autopilot-coupled descent phase of flight, which have been
attributed to jammed or frozen pitch trim actuators. That condition, if
not corrected, could result in reduced controllability of the airplane.
New Relevant Service Information
The original NPRM cited EMBRAER Service Bulletin 120-25-0262, dated
October 15, 2001, and Change 01, dated September 3, 2002, as the
appropriate sources of service information for installing the placards.
Since we issued the original NPRM, EMBRAER revised the service
bulletin. Change 02, dated October 30, 2003, recommends revised
[[Page 7495]]
placard language that clarifies that the pitch trim system is to be
checked only before the initial descent.
EMBRAER has issued Service Bulletins 120-27-0095 and 120-27-0096,
both dated February 16, 2007, which describe procedures for modifying
the elevator trim system. Service Bulletin 120-27-0095 describes
procedures for replacing the elevator trim tab actuators with new ones
that have been developed using corrosion-resistant internal materials
and other improvements, including a damper coupled to one of the two
actuators. Service Bulletin 120-27-0096 describes procedures for
replacing some segments of the elevator trim tab control cables. The
replacement segments have a different diameter, and have been developed
to contribute to the new actuator dampening function specified in
Service Bulletin 120-27-0095.
Accomplishing the actions specified in the service information is
intended to adequately address the unsafe condition. The Ag[ecirc]ncia
Nacional de Avia[ccedil]o Civil (ANAC), which is the airworthiness
authority for Brazil, mandated the service information and issued
Brazilian airworthiness directive 2001-06-01R4, effective August 23,
2007, to ensure the continued airworthiness of these airplanes in
Brazil.
Comments
Due consideration has been given to the comments received in
response to the original NPRM.
Support for Original NPRM
SkyWest Airlines concurs with the proposed requirement to revise
the Limitations section of the Collins APS-65B Autopilot AFM
Supplement. The Air Line Pilots Association (ALPA) concurs
(conditionally, based on its comments as discussed below) with the
proposed actions.
Request for Appropriate Solution for Mechanical Problem
ALPA asserts that the original NPRM would implement an operational
fix to address a mechanical problem, and requests that we revise the
original NPRM to adequately correct the unsafe condition. ALPA notes
that the original NPRM addresses pitch trim actuators that freeze in
position when moisture accumulates at colder temperatures. ALPA
requests that the FAA and EMBRAER identify the extent of water
intrusion in this area and look into a mechanical means to preclude the
actuators from jamming. ALPA also notes that the original NPRM does not
identify the cause of the jammed pitch trim actuators. ALPA explains
that pitch trim actuators have become mechanically jammed on other
EMBRAER aircraft due to insufficient power available from the actuator.
If the cause of the jamming can be mechanical, ALPA requests that the
FAA and the manufacturer identify a means to preclude such a failure.
We agree. In this supplemental NPRM, we consider the AFM revisions
and placards to be interim solutions, and propose to also mandate the
modifications described in Service Bulletins 120-27-0095 and 120-27-
0096, which would terminate the proposed requirements to revise the AFM
and install the placards.
Assertion Regarding Jamming Conditions
The commenter, Thomas Kuhlman, states that the original NPRM
apparently assumes that all or most of the jamming occurs during cruise
flight. Mr. Kuhlman instead asserts, based on the supportive data that
accompany his comment, that the pitch trim actuator jamming can and
does occur when moisture is present in freezing conditions.
Although Mr. Kuhlman makes no specific request regarding the
original NPRM's proposed requirements, we agree with his rationale.
When actuator internal frictions are within their normal specified
ranges, the system can manage normal envelope load increases attributed
to events such as speed variations and cold soak environment icing, so
a jam attributable solely to a cold soak environment is unlikely. If
contamination is gradually occurring inside the actuators, the proposed
manual checks of the pitch trim systems on initial descent on every
flight will inform the flight crew of degraded system performance, and
affected actuators would then be removed before they reach a condition
that could lead to a complete jam. In any event, as stated previously,
we have revised this supplemental NPRM to require modifications that
will adequately address the commenter's concerns.
Request To Allow Autopilot Re-Engagement Under Certain Conditions
SkyWest concurs with the proposed requirement in the original NPRM
to revise the elevator trim jamming procedure specified in the flight
controls failure paragraph of the AFM abnormal procedures section, but
requests that we allow the flight crew to re-engage the autopilot once
pitch trim is recovered. The commenter asserts that SkyWest's
experience suggests that, once normal elevator trim operation was
restored, continued use of the autopilot did not result in any abnormal
operation.
We disagree. When free pitch trim is restored after jamming, the
appropriate approach is to continue the flight manually without the
autopilot and report the issue to maintenance, rather than re-engaging
the autopilot, so the cause of the jam can be evaluated and corrected
before further use of the autopilot. We have not changed the
supplemental NPRM regarding this issue.
Request To Revise AFM Normal Procedures
SkyWest reports that its EMB-120 SOP already includes an advisory
to check the pitch trim before initiating a descent if trim jamming is
suspected. The commenter requests that we revise the original NPRM to
include these revised procedures in the descent checklist in the AFM's
normal procedures section.
We acknowledge that conducting such checks whenever a trim system
jam is suspected is a reasonable practice. But conducting such manual
checks of the pitch trim system at every flight before initial descent
on autopilot is a more effective approach because it will detect
jamming before it is suspected. We have not changed the supplemental
NPRM regarding this issue.
Request To Revise Placard Language
SkyWest asserts that the placard language proposed in the original
NPRM, which specifies a check before any (all) descents, will
compromise the safe operation of Model EMB-120 airplanes. The commenter
reports that it is not unusual to level off at intermediate altitudes
four to eight times during descent from cruise altitude and approach,
depending on cruise altitude, terminal area requirements, and type of
approach. As a result, the proposed limitation would require the pilot
to disconnect the autopilot during flight an equal number of times,
including just before ILS glide slope intercept. The commenter requests
that we change the proposed placard language to the following:
``Perform pitch trim system check prior to initial descent and anytime
elevator trim jamming is suspected.'' According to the commenter,
limiting the checks in this way would ensure that the check is
completed at least once per flight (consistent with EMBRAER's
recommendations from the 2002 World Wide Operators Conference), but
mandating a check before every descent would create a distraction,
[[Page 7496]]
unnecessarily increase pilot workload, and compromise safety.
We partially agree. EMBRAER has revised the placard language to
require trim system checks only before initial descent. Manually
checking the system when jamming is suspected would be a natural
reaction, so it is not necessary to add the extra requested words to
the placard. We have revised paragraph (c) in this supplemental NPRM to
mandate Change 02 of the service bulletin.
Request To Remove Placard Requirement: Potential Pilot Distraction
The commenter, Thomas Kuhlman, feels that the proposed requirement
to test the trim system before every descent could result in little
effect, or even decreased safety due to pilot distraction, during
arrival procedures with multiple descents. He also notes that most
precision approaches have a level flight segment just before glide
slope intercept. The AD as proposed would require an elevator trim test
at the critical glide slope intercept.
We infer the commenter wants us to remove the proposed requirement
to install the placards. We partially agree. We agree with the
manufacturer's recommendation to check the system manually before
initial descent only. As we stated previously, the placard language has
been revised in Change 02 of Service Bulletin 120-25-0262, and in
corresponding paragraph (c) of this supplemental NPRM, to clarify that
such checks are necessary only before the initial descent of every
flight. Limiting the number of checks in this way would maintain the
safety of the fleet and still address the commenter's concern about
potential pilot distraction during critical phases of flight.
Request To Remove Placard Requirement: Inadequate Solution
The commenter, SkyWest Airlines, states that merely installing the
placards as proposed in the original NPRM would not adequately address
the problem of elevator trim jamming. The commenter notes that this
procedure would be inconsistent with its findings: In the 18 months
before the original NPRM was issued, there were ten incidents involving
elevator trim jamming; of these, four occurred in the descent phase of
flight, four occurred in the cruise phase of flight, and two occurred
during climb to cruise altitude. The commenter concludes that advising
the flight crew to perform a pitch trim check only during descent will
not prevent problems associated with pitch upset.
We infer that the commenter wants us to require revised procedures
during other phases of flight. We partially agree. We agree that the
pitch trim can jam during any phase of flight. But while the data
provided by SkyWest might reflect results for SkyWest, the fleet data
suggest that most of the reported events occurred during the descent
phase or during transition from cruise to descent. The possibility that
a pitch trim jam can occur during any flight phase does not render the
proposed approach ineffective. The multiple system checks will assist
in reducing the possibility of a pitch oscillation event due to
actuator performance degradation. Since the comment was submitted, we
revised this supplemental NPRM to add the modifications of the elevator
trim system, which will address the identified unsafe condition and
eliminate the need for the placards.
Explanation of Additional Changes to Original NPRM
We have revised the applicability identified in the original NPRM
to identify model designations as published in the most recent type
certificate data sheet for the affected models.
To correspond with the ANAC AD, we have revised paragraph (b) of
this supplemental NPRM to specify that the revised AFM language in that
paragraph also be included in the Normal Procedures section (in
addition to the Limitations section) of the autopilot system
supplement.
Conclusion
Since certain changes described above expand the scope of the
originally proposed rule, the FAA has determined that it is necessary
to reopen the comment period to provide additional opportunity for
public comment.
Cost Impact
The following table provides the estimated costs for U.S. operators
to comply with this supplemental NPRM.
Estimated Costs
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Number of
Average Cost per U.S.-
Action Work hours labor rate Parts product registered Fleet cost
per hour airplanes
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AFM revisions............... 1 $80 $0 $80 103 $8,240
Placard installation........ 2 80 182 342 103 35,226
Actuator replacement........ 7 80 16,670 17,230 103 1,774,690
Cable replacement........... 14 80 1,050 2,170 103 223,510
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The cost impact figures discussed above are 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.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, Section 106, describes the
authority of the FAA Administrator. Subtitle VII, Aviation Programs,
describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701, ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.
[[Page 7497]]
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:
Empresa Brasileira De Aeronautica S.A. (Embraer): Docket 2003-NM-33-
AD.
Applicability: All Model EMB-120, -120ER, -120FC, -120QC, and -
120RT airplanes, certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
To prevent pitch trim upsets if the pitch trim actuators jam or
freeze, which could result in reduced controllability of the
airplane, accomplish the following:
Revision of Airplane Flight Manual (AFM): AFM-120/794
(a) Within 100 flight hours after the effective date of this AD,
revise the FAA-approved AFM, EMBRAER AFM-120/794, as specified in
paragraphs (a)(1) and (a)(2) of this AD. These actions may be
accomplished by inserting a copy of this AD into the AFM.
(1) Revise the FLIGHT CONTROLS FAILURES paragraph of the
Abnormal Procedures section by replacing the existing ELEVATOR TRIM
JAMMING procedure with the following:
``ELEVATOR TRIM JAMMING
Control Wheel...................... Hold Firmly.
Autopilot........................... Disengage.
Airspeed............................ Reduce.
NOTE: Minimum airspeed with flap 0 [deg]--160 KIAS
Pitch trim command................. Check all switches and elevator
trim wheel.
If pitch trim is recovered:
Re-trim the airplane and continue the flight with the autopilot
disengaged, not exceeding the airspeed when the trim was recovered.
.
If pitch trim is not recovered:
Land at the nearest suitable
airport.
Approach and landing configuration:
Landing gear.................... Down.
Flaps........................... 25.
Airspeed........................ Vref25.
CAUTION: DO NOT TRY TO RE-ENGAGE THE AUTOPILOT.''
(2) Revise the Normal Procedures section of the AFM, after the current
checklist item for activating the FASTEN BELTS switch, by inserting the
following:
``PITCH TRIM SYSTEM CHECK
Control Wheel...................... Hold firmly.
Autopilot........................... Disengage.
Power Levers........................ As required.
Elevator Trim Wheels................ As required.
CAUTION: MANUALLY SET THE ELEVATOR TRIM WHEELS TO THE REQUIRED DESCENT
ATTITUDE.
If any trim system binding (if trim wheel rotates more than one trim
wheel index mark after being released), or abnormal trim operation is
observed:
Elevator Trim Jamming Procedure. Perform.
CAUTION: DO NOT TRY TO RE-ENGAGE THE AUTOPILOT.
If no abnormal trim operation is
observed:
Flight Director Vertical Mode... As required.
Autopilot....................... Reengage.''
AFM Revision: Collins APS-65B Autopilot AFM Supplement
(b) Concurrently with the AFM revisions required by paragraph
(a) of this AD, revise the Limitations section of the Collins APS-
65B Autopilot System Supplement to include the following (this may
be accomplished by inserting a copy of this AD into the AFM
Supplement):
``(1) The autopilot must not be used during descent unless a trim check
has been performed successfully prior to descent, as follows:
PITCH TRIM SYSTEM CHECK
Control Wheel....................... Hold firmly.
[[Page 7498]]
Autopilot........................... Disengage.
Power Levers........................ As required.
Elevator Trim Wheels................ As required.
CAUTION: MANUALLY SET THE ELEVATOR TRIM WHEELS TO THE REQUIRED DESCENT
ATTITUDE.
If any trim system binding (if trim wheel rotates more than one trim
wheel index mark after being released), or abnormal trim operation is
observed:
Elevator Trim Jamming Procedure. Perform.
CAUTION: DO NOT TRY TO RE-ENGAGE THE AUTOPILOT.
If no abnormal trim operation is observed:
Flight Director Vertical Mode... As required.
Autopilot....................... Reengage.
``(2) If an elevator trim jamming is detected during flight and the
pitch trim system resumes normal operation on ground, only a ferry
flight using a special permit may be performed to return the aircraft
to a maintenance base for replacement of the actuators. In this case,
the use of autopilot is prohibited.''
Placard Installation
(c) Within 300 flight hours after the effective date of this AD,
install two placards on the glareshield, advising the flight crew to
check the pitch trim before initial descent, in accordance with Part
II of the Accomplishment Instructions of EMBRAER Service Bulletin
120-25-0262, Change 02, dated October 30, 2003.
Elevator Trim System Modification
(d) Within 36 months after the effective date of this AD, modify
the elevator trim system, in accordance with the Accomplishment
Instructions of EMBRAER Service Bulletin 120-27-0095 and 120-27-
0096, both dated February 16, 2007. Accomplishment of the
modification terminates the requirements of paragraphs (a), (b), and
(c) of this AD, and the corresponding AFM revisions and placards may
be removed.
Parts Installation
(e) As of 36 months after the effective date of this AD, no
person may install, on any airplane, an elevator trim tab actuator
or control cable having a part number identified in Table 1 of this
AD.
Table 1.--Prohibited Parts
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Part Part No.
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Elevator trim tab actuator................ 120-19685-001
120-19685-003
120-19685-007
120-38650-001
120-39205-001
5299
5299-1
Control cable............................. 120-27729-095
120-27729-097
120-31370-095
120-31370-097
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Alternative Methods of Compliance
(f)(1) The Manager, International Branch, ANM-116, Transport
Airplane Directorate, FAA, has the authority to approve AMOCs for
this AD, if requested in accordance with the procedures found in 14
CFR 39.19.
(2) To request a different method of compliance or a different
compliance time for this AD, follow the procedures in 14 CFR 39.19.
Before using any approved AMOC on any airplane to which the AMOC
applies, notify your appropriate principal inspector (PI) in the FAA
Flight Standards District Office (FSDO), or lacking a PI, your local
FSDO.
Note 1: The subject of this AD is addressed in Brazilian
airworthiness directive 2001-06-01R4, effective August 23, 2007.
Issued in Renton, Washington, on February 1, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E8-2356 Filed 2-7-08; 8:45 am]
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