[Federal Register Volume 59, Number 209 (Monday, October 31, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-26876]
[[Page Unknown]]
[Federal Register: October 31, 1994]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 91-CE-46-AD]
Airworthiness Directives; de Havilland DHC-6 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes to supersede Airworthiness Directive
(AD) 83-18-03, which currently requires repetitively inspecting the
tailplane outboard hinge assembly for cracks on certain de Havilland
DHC-6 series airplanes, and replacing any cracked part. The Federal
Aviation Administration's policy on aging commuter-class aircraft is to
eliminate, or in certain instances, reduce the number of certain
repetitive short-interval inspections when improved parts or
modifications are available. The proposed action would require
eventually modifying the tailplane outboard hinge arm and tailplane
hinge plate as terminating action for the currently required repetitive
inspections. The actions specified in the proposed AD are intended to
prevent tailplane failure caused by cracks in either the outboard hinge
arm or the hinge plate.
DATES: Comments must be received on or before January 4, 1995.
ADDRESSES: Submit comments on the proposal in triplicate to the Federal
Aviation Administration (FAA), Central Region, Office of the Assistant
Chief Counsel, Attention: Rules Docket No. 91-CE-46-AD, Room 1558, 601
E. 12th Street, Kansas City, Missouri 64106. Comments may be inspected
at this location between 8 a.m. and 4 p.m., Monday through Friday,
holidays excepted.
Service information that applies to the proposed AD may be obtained
from de Havilland, Inc., 123 Garratt Boulevard, Downsview, Ontario,
Canada, M3K1Y5. This information also may be examined at the Rules
Docket at the address above.
FOR FURTHER INFORMATION CONTACT: Jon Hjelm, Aerospace Engineer, FAA,
New York Aircraft Certification Office, 181 South Franklin Avenue, Room
202, Valley Stream, New York 11581; telephone (516) 791-6220; facsimile
(516) 791-9024.
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 should 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 that summarizes 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 No. 91-CE-46-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, Central Region, Office of the Assistant Chief Counsel,
Attention: Rules Docket No. 91-CE-46-AD, Room 1558, 601 E. 12th Street,
Kansas City, Missouri 64106.
Discussion
The FAA has determined that reliance on critical repetitive
inspections on aging commuter-class airplanes carries an unnecessary
safety risk when a design change exists that could eliminate, or in
certain instances, reduce the number of those critical inspections. In
determining what inspections are critical, the FAA considers (1) the
safety consequences of the airplane if the known problem is not
detected by the inspection; (2) the reliability of the inspection such
as the probability of not detecting the known problem; (3) whether the
inspection area is difficult to access; and (4) the possibility of
damage to an adjacent structure as a result of the problem.
These factors have led the FAA to establish an aging commuter-class
aircraft policy that requires incorporating a known design change when
it could replace a critical repetitive inspection. With this policy in
mind, the FAA recently conducted a review of existing AD's that apply
to de Havilland DHC-6 series airplanes. Assisting the FAA in this
review were (1) Transport Canada, which is the airworthiness authority
for Canada; (2) de Havilland, Inc.; (3) the Regional Airlines
Association (RAA); and (4) several U.S. and foreign operators of the
affected airplanes.
From this review, the FAA has identified AD 83-18-03, Amendment 39-
1658, as one that should be superseded with a new AD that would
eliminate short-interval and critical repetitive inspections. AD 83-18-
03 currently requires repetitively inspecting the tailplane outboard
hinge assembly for cracks on certain de Havilland DHC-6 series
airplanes, and replacing any cracked part.
De Havilland, Inc. (formerly Boeing of Canada, Ltd.) has issued
Service Bulletin (SB) No. 6/421, Revision B, dated November 11, 1983.
This service bulletin specifies procedures for replacing the tailplane
outboard hinge arm and tailplane hinge plate with parts of improved
design. This replacement is known as Modification No. 6/1799.
As a result of the previously discussed AD review, Transport Canada
considers Modification 6/1799 mandatory and has issued Transport Canada
AD CF-83-11 in order to assure the continued airworthiness of these
airplanes in Canada.
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, Transport Canada has kept the FAA
informed of the situation described above.
Based on its aging commuter-class aircraft policy and after
reviewing all available information including that received from
Transport Canada, the FAA has determined that AD action should be taken
to eventually eliminate the repetitive short-interval inspections
required by AD 83-18-03, and to prevent tailplane failure caused by
cracks in either the outboard hinge arm or the hinge plate.
Since an unsafe condition has been identified that is likely to
exist or develop in other de Havilland DHC-6 series airplanes of the
same type design, the proposed AD would supersede AD 83-18-03 with a
new AD that would (1) initially retain the requirement of repetitively
inspecting the tailplane outboard hinge assembly for cracks, and
replacing any cracked part; and (2) eventually require modifying the
tailplane outboard hinge arm and tailplane hinge plate with parts of
improved design (Modification No. 1799) as terminating action for the
currently required repetitive inspections. The proposed actions would
be accomplished in accordance with de Havilland SB No. 6/421, Revision
B, dated November 11, 1983.
The FAA estimates that 141 airplanes in the U.S. registry would be
affected by the proposed AD, that it would take approximately 35
workhours per airplane to accomplish the proposed action, and that the
average labor rate is approximately $60 an hour. Parts cost
approximately $4,400 per airplane. Based on these figures, the total
cost impact of the proposed AD on U.S. operators is estimated to be
$916,500. This figure is based on the assumption that no affected
airplane owner/operator has accomplished the proposed action.
The intent of the FAA's aging commuter airplane program is to
ensure safe operation of commuter-class airplanes that are in
commercial service without adversely impacting private operators. Of
the approximately 141 airplanes in the U.S. registry that would be
affected by the proposed AD, the FAA has determined that approximately
40 percent are operated in scheduled passenger service. A significant
number of the remaining 60 percent are operated in other forms of air
transportation such as air cargo and air taxi.
The proposed AD allows 2,400 hours time-in-service (TIS) before
mandatory accomplishment of the design modification. The average
utilization of the fleet for those airplanes in commercial commuter
service is approximately 25 to 50 hours TIS per week. Based on these
figures, operators of commuter-class airplanes involved in commercial
operation would have to accomplish the proposed modification within 12
to 24 calendar months after the proposed AD would become effective. For
private owners, who typically operate between 100 to 200 hours TIS per
year, this would allow 12 to 24 years before the proposed modification
would be mandatory.
The following paragraphs present cost scenarios for airplanes where
no cracks are found and where cracks are found, utilizing an average
remaining airplane life of 15 years and an average annual utilization
rate of 1,600 hours TIS. A copy of the full Cost Analysis and
Regulatory Flexibility Determination for the proposed action may be
examined at the FAA, Central Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 91-CE-46-AD, Room 1558, 601 E.
12th Street, Kansas City, Missouri.
No Cracks Scenario: Under the provisions of AD 83-18-03,
an owner/operator of a de Havilland DHC-6 series airplane in scheduled
service who operates an average of 1,600 hours TIS annually would
inspect every 1,200 hours TIS. This would amount to a remaining
airplane life (estimated 15 years) amount of $4,769; this figure is
based on the assumption that no cracks are found during the
inspections. The proposed AD would incur the same 1,200-hour TIS
inspection until 2,400 hours TIS where the operator would have to
replace the tailplane outboard hinge arm assembly (eliminating the need
for further repetitive inspections), which would result in a present
value cost of $6,574. The incremental cost of the proposed AD for such
an airplane would be $1,805 ($6,574-$4,769) or $1,309 annualized over
the 1.5 years it would take to accumulate 2,400 hours TIS. An owner of
a general aviation airplane who operates 800 hours TIS annually without
finding any cracks during the 1,200-hour TIS inspections would incur a
present value incremental cost of $3,843 ($5,990-$2,507). This would
amount to a per year amount of $1,327 over the three years it would
take to accumulate 2,400 hours TIS.
Cracks Found Scenario: Under the provisions of AD 83-18-
03, an owner/operator of a de Havilland DHC-6 series airplane who found
cracks during an inspection would have to repair the crack prior to
further flight and resume inspections every 1,200 hours TIS. The
proposed AD would require immediate replacement of the arm assembly if
cracks were found as terminating action for the repetitive inspection
requirement. The repair cost is the same as the replacement except that
the repair does not terminate the inspection requirement. For this
reason, the proposed AD would result in present-day cost savings, which
would continue to grow over the remaining life of the airplane since
repetitive inspections would not be required. Using the assumed 15-year
remaining life, the cost savings would be $4,409 for scheduled service
airplane owners/operators and $2,149 for general aviation airplane
owners/operators.
The Regulatory Flexibility Act of 1980 (RFA) was enacted by
Congress to ensure that small entities are not unnecessarily or
disproportionally burdened by government regulations. The RFA requires
government agencies to determine whether rules would have a
``significant economic impact on a substantial number of small
entities,'' and, in cases where they would, conduct a Regulatory
Flexibility Analysis in which alternatives to the rule are considered.
FAA Order 2100.14A, Regulatory Flexibility Criteria and Guidance,
outlines FAA procedures and criteria for complying with the RFA. Small
entities are defined as small businesses and small not-for-profit
organizations that are independently owned and operated or airports
operated by small governmental jurisdictions. A ``substantial number''
is defined as a number that is not less than 11 and that is more than
one-third of the small entities subject to a proposed rule, or any
number of small entities judged to be substantial by the rulemaking
official. A ``significant economic impact'' is defined by an annualized
net compliance cost, adjusted for inflation, which is greater than a
threshold cost level for defined entity types. FAA Order 2100.14A sets
the size threshold for small entities operating aircraft for hire at 9
aircraft owned and the annualized cost thresholds, adjusted to 1994
dollars, at $69,000 for scheduled operators and $4,850 for unscheduled
operators.
Of the 141 U.S.-registered airplanes affected by the proposed AD, 6
airplanes are owned by the federal government. Of the other 135, one
business owns 26 airplanes, one business owns 9 airplanes, one business
owns 8 airplanes, 1 business owns 7 airplanes, one business owns 4
airplanes, two businesses own 3 airplanes each, thirteen business own 2
airplanes each, and forty-nine businesses each own 1 airplane.
Because the FAA has no readily available means of obtaining data on
sizes of these entities, the economic analysis for the proposed AD
utilizes the worst case scenario using the lower annualized cost
threshold of $4,850 for operators in unscheduled service instead of
$69,000 for operators in scheduled service. With this in mind and based
on the above ownership distribution, the 64 entities owning 3 or fewer
airplanes would not experience a ``significant economic impact'' as
defined by FAA Order 2100.14A. Since the remaining five entities do not
constitute a ``substantial number'' as defined in the Order, the
proposed AD would not have a ``significant economic impact on a
substantial number of small entities.''
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 action (1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under 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 has been placed 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. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing AD 83-18-03, Amendment 39-
4719, and adding a new AD to read as follows:
De Havilland: Docket No. 91-CE-46-AD. Supersedes AD 83-18-03,
Amendment 39-4719.
Applicability: Models DHC-6-1, DHC-6-100, DHC-6-200 and DHC-300
airplanes (serial numbers 1 to 810), certificated in any category,
that have not incorporated Modification 6/1799 in accordance with
the ACCOMPLISHMENT INSTRUCTIONS, Replacement, section of de
Havilland Service Bulletin (SB) No. 6/421, Revision B, dated
November 11, 1983.
Compliance: Required as indicated in the body of this AD, unless
already accomplished.
To prevent tailplane failure caused by cracks in either the
outboard hinge arm or the hinge plate, accomplish the following:
(a) Within the next 50 hours time-in-service (TIS) after the
effective date of this AD or within the next 1,200 hours TIS after
the last inspection accomplished in accordance with superseded AD
83-18-03, Amendment 39-4719, whichever occurs later, inspect the
tailplane outboard hinge arm assembly for cracks in accordance with
the ACCOMPLISHMENT INSTRUCTIONS, Inspection, section of de Havilland
SB No. 6/421, Revision B, dated November 11, 1983.
(1) If cracks are not found, reinspect every 1,200 hours TIS
until Modification 6/1799 (tailplane outboard hinge arm and
tailplane hinge plate) is installed as required by paragraph (b) of
this AD.
(2) If cracks are found, prior to further flight, replace the
tailplane outboard hinge arm assembly with Modification 6/1799 in
accordance with the ACCOMPLISHMENT INSTRUCTIONS, Replacement,
section of de Havilland SB No. 6/421, Revision B, dated November 11,
1983.
(b) Within 2,400 hours TIS after the effective date of this AD,
replace the tailplane outboard hinge arm assembly with Modification
6/1799 in accordance with the ACCOMPLISHMENT INSTRUCTIONS,
Replacement, section of de Havilland SB No. 6/421, Revision B, dated
November 11, 1983, unless already accomplished in accordance with
paragraph (a)(2) of this AD.
(c) Compliance with paragraph (a)(2) or (b) of this AD is
considered terminating action for the inspection requirements of
this AD.
(d) 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.
(e) An alternative method of compliance or adjustment of the
initial or repetitive compliance times that provides an equivalent
level of safety may be approved by the Manager, New York Aircraft
Certification Office (ACO), FAA, 181 South Franklin Avenue, Room
202, Valley Stream, New York 11581. The request shall be forwarded
through an appropriate FAA Maintenance Inspector, who may add
comments and then send it to the Manager, New York ACO.
Note: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the New York ACO.
(f) All persons affected by this directive may obtain copies of
the document referred to herein upon request to de Havilland, Inc.,
123 Garratt Boulevard, Downsview, Ontario M3K 1Y5 Canada; or may
examine this document at the FAA, Central Region, Office of the
Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City,
Missouri 64106.
Issued in Kansas City, Missouri, on October 25, 1994.
John R. Colomy,
Acting Manager, Small Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-26876 Filed 10-28-94; 8:45 am]
BILLING CODE 4910-13-P
