[Federal Register Volume 61, Number 203 (Friday, October 18, 1996)]
[Proposed Rules]
[Pages 54364-54366]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-26707]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-NM-242-AD]
RIN 2120-AA64
Airworthiness Directives; Airtell International, Inc., Centaurus
Model C3-100 Ground Proximity Warning System (GPWS), as Installed in
Various 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 all Airtell International, Inc.,
Centaurus Model C3-100 GPWS equipment that is installed on any type of
airplane. This proposal would require replacement of this equipment
with a similar type of equipment that meets specific performance
requirements. This proposal is prompted by results of an investigation,
which revealed that, under certain circumstances, the Centaurus GPWS
equipment does not provide the flight crew with aural warnings to
indicate that the airplane is descending. The actions specified by the
proposed AD are intended to prevent failure of the GPWS equipment to
provide such aural warnings. If the flight crew relies on receiving
such warnings and the GPWS equipment fails to provide those warnings,
the ability of the flight crew to prevent the airplane from impacting
the ground may be inhibited.
DATES: Comments must be received by November 25, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-242-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.
Information concerning this proposal may be obtained from or
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue,
SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: John P. Dimtroff, Aerospace Engineer,
Flight Test and Systems Branch, ANM-111, FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056;
telephone (206) 227-2117; fax (206) 227-1100.
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 notice may be changed in
light of the comments received.
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 notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 96-NM-242-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-103, Attention: Rules
Docket No. 96-NM-242-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
Section 135.153 of the Federal Aviation Regulations (14 CFR
135.153) specifies that no turbine-powered airplane having a passenger
seating configuration (excluding any pilot seat) of 10 or more seats
may be operated unless the airplane is equipped with an approved ground
proximity warning system (GPWS). In order to be considered approved,
GPWS equipment must meet certain minimum performance standards
prescribed in Technical Standard Order (TSO) C-92b, dated August 19,
1976. That TSO references Radio Technical Commission for Aeronautics
(RTCA) Document No. DO-161A, ``Minimum Performance Standards, Airborne
Ground Proximity Warning Equipment,'' dated May 27, 1976, as an
additional source of information. The RTCA document indicates that the
minimum performance standards are a means of ensuring that GPWS
equipment will satisfactorily perform its intended function under all
conditions normally encountered in routine aeronautical operations.
The FAA has received reports indicating that Centaurus Model C3-100
GPWS equipment, which is installed in various transport, commuter, and
normal category airplanes, does not meet the minimum performance
standards prescribed in TSO C-92b.
GPWS Equipment, in General
The GPWS equipment is an aid to the flight crew for determining the
imminent occurrence of inadvertent contact of the airplane with the
ground. This equipment is intended to supplement flight instrument
data, which alerts the flight crew that inadvertent contact with the
ground may occur. The GPWS equipment must provide indications of
proximity to the ground in the following modes of aircraft operation:
Mode 1. Excessive rates of descent;
Mode 2. Excessive closure rate to terrain;
Mode 3. Negative climb rate or altitude loss after takeoff;
Mode 4. Flight into terrain when not in landing configuration; and
Mode 5. Excessive downward deviation from an instrument landing
system (ILS) glide slope.
Distinctive aural warnings must be provided for Modes 1 through 4
above. The aural warning for these modes must consist of the sound
``Whoop-Whoop,'' followed by either ``Pull Up'' or ``Terrain'' (or
other acceptable annunciation), which is repeated until the hazardous
condition no longer exists.
Results of FAA Testing
Subsequent to the reports discussed previously, the FAA conducted
testing of two Centaurus Model C3-100 GPWS
[[Page 54365]]
units in accordance with RTCA Document No. DO-161A. Results of that
testing confirmed that Centaurus Model C3-100 GPWS equipment does not
meet all minimum performance standards specified in TSO C-92b and RTCA
Document No. DO-161A. Specifically, failures occurred in Mode 2
(excessive descent rate) and Mode 3 (descent after takeoff) of aircraft
operation.
The FAA has determined that the effect of the deficiencies found in
Modes 2 and 3 could result in an unsafe condition. Those deficiencies
are as follows:
1. Mode 2A2. Using a start altitude of 2,450 feet, the FAA tested
the GPWS equipment and listened for aural warnings issued at terrain
closure rates from 2,500 to 7,000 feet per minute (fpm). At closure
rates of 3,750 fpm and below, no warnings were received within the
acceptable range. Warnings were issued at parameters outside specified
minimum performance requirements.
2. Mode 2A4. Using a start altitude of 2,450 feet, the FAA tested
the GPWS equipment and listened for warnings issued at terrain closure
rates from 2,500 to 7,000 fpm. Valid warnings were received at closure
rates within the acceptable band until descent rates decreased to less
than 3,500 fpm. Descent rates of less than 3,500 fpm yielded alarms
outside the prescribed minimum performance requirements.
3. Mode 2B1. Using a start altitude of 2,450 feet, the FAA tested
the GPWS equipment and listened for warnings issued at terrain closure
rates from 2,500 to 7,000 fpm. Valid warnings were received at closure
rates within the acceptable band until descent rates decreased to less
than 3,200 fpm. Descent rates of less than 3,200 fpm yielded alarms
outside the prescribed minimum performance requirements.
4. Mode 3B. Simulating takeoff from zero feet radio altitude to 700
feet, the BARO rate (altitude loss) parameter was increased in 20-foot
increments from 20 to 140 feet, and then to 500 and 1,000 feet. After
numerous attempts, valid results could not be obtained, i.e., neither
unit tested issued a warning at 140 feet (or less) altitude loss. At an
altitude loss value above 140 feet, warnings were noted; however, these
warnings were intermittent at times.
FAA's Findings
Concerning Mode 2, the FAA finds that Centaurus Model C3-100 GPWS
equipment does not provide the flight crew with appropriate aural
warnings of encroaching terrain when the rate of descent of the
airplane is 3,750 feet per minute or less at altitudes of 1,000 feet or
below.
In addition, regarding Mode 3, when an airplane is descending after
takeoff, Centaurus Model C3-100 GPWS equipment does not provide an
aural warning (``DON'T SINK'') when a barometric altitude loss of 140
feet or less is encountered to indicate that the airplane is descending
after takeoff.
FAA's Conclusions
It is reasonable to assume that flight crews may come to rely on
the aural warnings that should be provided by GPWS equipment during
Modes 2 and 3 of aircraft operation. If the flight crew relies on
receiving such warnings and the GPWS equipment fails to provide those
warnings, the ability of the flight crew to prevent the airplane from
impacting the ground may be inhibited.
Explanation of Requirements of Proposed Rule
Since an unsafe condition has been identified that is likely to
exist on other products of this same type design, the proposed AD would
require removal and replacement of Centaurus Model C3-100 GPWS
equipment with a similar type of equipment that meets specific
performance requirements. The actions would be required to be
accomplished in accordance with a method approved by the FAA.
It also may be possible to correct the addressed unsafe condition
by modifying the unit. However, the FAA has not identified any
particular means by which such a modification may be accomplished. The
FAA would consider a request for approval of an alternative method of
compliance, in accordance with the provisions of this proposed AD,
provided that adequate justification is presented to support such a
request.
Cost Impact
The FAA estimates that 30 airplanes of U.S. registry would be
affected by this proposed AD, that it would take approximately 20 work
hours per airplane to accomplish the proposed actions, and that the
average labor rate is $60 per work hour. Required parts would cost
approximately $16,000 per airplane. Based on these figures, the cost
impact of the proposed AD on U.S. operators is estimated to be
$516,000, or $17,200 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.
Regulatory Impact
The regulations proposed herein would not have substantial direct
effects 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, in
accordance with Executive Order 12612, it is determined that this
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
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:
Airtell International, Inc.: Docket 96-NM-242-AD.
Applicability: Centaurus Model C3-100 ground proximity warning
system (GPWS) equipment, as installed in, but not limited to, the
following airplanes, certificated in any category:
Beech 99 series airplanes;
Beech 200 series airplanes;
Dassault Aviation Model Mystere-Falcon 200 series airplanes;
EMBRAER (Empresa Brasileira de Aeronautica S.A.) EMB-110 series
airplanes;
[[Page 54366]]
Fairchild Aircraft Model SA226-TC series airplanes;
Fairchild Aircraft Model SA227-AT series airplanes; and
Grumman Model G-73 Mallard airplanes.
Compliance: Required as indicated, unless accomplished
previously.
To prevent failure of the GPWS equipment to provide certain
aural warnings, which could inhibit the ability of the flight crew
to prevent the airplane from impacting the ground, accomplish the
following:
(a) Within 60 days after the effective date of this AD, remove
and replace Centaurus Model C3-100 GPWS equipment with a similar
type of equipment that meets minimum performance standards specified
in Technical Standard Order (TSO) C-92b, dated August 19, 1976.
Accomplish the actions in accordance with a method approved by the
Manager, Flight Test and Systems Branch, ANM-111, FAA, Transport
Airplane Directorate.
(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, Flight Test and Systems Branch,
ANM-111. Operators shall submit their requests through an
appropriate FAA Principal Maintenance Inspector, who may add
comments and then send it to the Manager, Flight Test and Systems
Branch, ANM-111.
Note: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Manager, Flight Test and Systems Branch, ANM-111.
(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 October 9, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-26707 Filed 10-17-96; 8:45 am]
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