[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: 94-26878]
[[Page Unknown]]
[Federal Register: October 31, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 91-CE-22-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) 81-10-11, which currently requires repetitively inspecting the
elevator root ribs for cracks on 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 modifying the elevator root rib as
terminating action for the repetitive inspections that are currently
required by AD 81-10-11. The actions specified in the proposed AD are
intended to prevent failure of the elevator root rib, which could
result in loss of control of the airplane.
DATES: Comments must be received on or before January 4, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Central Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 91-CE-22-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, M3K 1Y5. 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-22-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-22-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) de Havilland; (2) the Regional Airlines Association
(RAA); and (3) several operators of the affected airplanes.
From this review, the FAA has identified AD 81-10- 11, Amendment
39-4112, as one that should be superseded with a new AD that would
require a modification that could eliminate the need for short-interval
and critical repetitive inspections. AD 81-10-11 currently requires
repetitively inspecting the elevator root rib for cracks on certain de
Havilland DHC-6 series airplanes, and replacing any cracked part.
De Havilland has issued Service Bulletin (SB) No. 6/399, Revision
E, dated May 25, 1984, which specifies procedures for (1) inspecting
the elevator root rib; and (2) modifying the elevator root rib
(Modification No. 6/1769). Modification No. 6/1769 consists of pulling
back the elevator skins, removing the torque tube assembly, replacing
the root rib assembly and doubler, replacing the second outboard nose
rib, installing a new intercostal, and reinstalling the torque tube
assembly and new skin.
This airplane model is manufactured in Canada and is 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, 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, the FAA has determined that AD
action should be taken to eliminate the repetitive short-interval
inspections required by AD 81-10-11, and to prevent failure of the
elevator root rib, which could result in loss of control of the
airplane.
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 that do not have Modification No. 6/1769 incorporated,
the proposed AD would supersede AD 81-10-11 with a new AD that would
(1) retain the current requirement of inspecting the elevator root rib
for cracks, and replacing any cracked part; and (2) require modifying
the elevator root rib (Modification 6/1769) as terminating action for
the repetitive inspections. The proposed actions would be accomplished
in accordance with de Havilland SB No. 6/399, Revision E, dated May 25,
1984.
The FAA estimates that 169 airplanes in the U.S. registry would be
affected by the proposed AD, that it would take approximately 54
workhours per airplane to accomplish the proposed action, and that the
average labor rate is approximately $60 an hour. Parts cost
approximately $4,200 per airplane. Based on these figures, the total
cost impact of the proposed AD on U.S. operators is estimated to be
$1,257,360. This figure is based upon the assumption that none of the
affected airplane owners/operators have incorporated Modification 6/
1769.
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 169 airplanes in the U.S. registry that would be
affected by the proposed AD, the FAA has determined that approximately
50 percent are operated in scheduled passenger service. A significant
number of the remaining 50 percent are operated in other forms of air
transportation such as air cargo and air taxi.
The following paragraphs present cost scenarios for airplanes where
no cracks were found and where cracks were found, utilizing an average
remaining airplane life of 15 years and an average annual utilization
rate of 1,600 hours TIS. De Havilland Models DHC-6-100 and DHC-6-200
airplanes have probably already accumulated 15,000 hours TIS;
therefore, those airplanes would have 100 hours TIS after the effective
date of the AD to incorporate Modification 6/1769. Some Model DHC-6-300
airplanes have not yet accumulated 15,000 hours TIS. This analysis is
based upon the assumption that these airplanes yet to accumulate 15,000
hours TIS have 10,000 hours TIS if operated in scheduled service and
5,000 hours TIS if operated in general aviation. 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-22-AD, Room
1558, 601 E. 12th Street, Kansas City, Missouri.
No Cracks Scenario for Models DHC-6-100 and DHC-6-200:
These airplanes would be inspected at 50 hours TIS after the effective
date and modified within 100 hours TIS after the effective date. The
incremental present value cost of the proposed AD over that required by
AD 81-10-11 is $5,919 for an airplane utilized in sheduled service, and
$6,642 for an airplane utilized in general aviation.
No Cracks Scenario for Model DHC-6-300 Airplanes: These
airplanes would be inspected at 50 hours TIS after the effective date
and thereafter at 600-hour TIS intervals until the elevator root rib is
replaced upon the accumulation of 15,000 hours TIS. The incremental
present value cost of the proposed AD over that required by AD 81-10-11
is $4,962 for an airplane utilized in sheduled service, and $3,099 for
an airplane utilized in general aviation.
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 169 U.S.-registered airplanes affected by the proposed AD, 6
airplanes are owned by the federal government. Of the other 163, one
business owns 26 airplanes, two businesses own 9 airplanes each, one
business owns 8 airplanes, one business owns 7 airplanes, one business
owns 5 airplanes, four businesses own 3 airplanes each, sixteen
businesses own 2 airplanes each, and fifty-five businesses own 1
airplane each.
Because the FAA has no readily available means of obtaining data on
the 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 proposed AD could have a
significant impact on a substantial number of small entities. Because
of this, the FAA conducted a regulatory flexibility analysis. A copy of
this analysis may be obtained by contacting the Rules Docket at the
location provided under the caption ADDRESSES.
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, may
have a significant economic impact on a substantial number of small
entities. The FAA has conducted an Initial Regulatory Flexibility
Determination and Analysis and has considered alternatives to this
proposal that could minimize the impact on small entities. A copy of
this analysis may be obtained by contacting the Rules Docket at the
location provided under the caption ADDRESSES. After careful
consideration, the FAA has determined that the proposed action is the
best course to achieve the safety objective of returning the airplane
to its original certification level of safety.
Alternative actions and views are solicited from interested persons
and will be considered by the FAA in the development of the final rule.
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 81-10-11, Amendment 39-
4112, and adding a new AD to read as follows:
De Havilland: Docket No. 91-CE-22-AD. Supersedes AD 81-10-11,
Amendment 39-4112.
Applicability: Models DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-
300 airplanes (all serial numbers), certificated in any category,
that do not have Modification No. 6/1769 incorporated.
Compliance: Required as indicated in the body of the AD, unless
already accomplished.
To prevent failure of the elevator root rib, which could result
in loss of control of the airplane, accomplish the following:
(a) Within the next 50 hours time-in-service (TIS) after the
effective date of this AD, unless already accomplished (compliance
with AD 81-10-11), inspect the elevator root rib, part number (P/N)
C6TE1022, for cracks in accordance with the ACCOMPLISHMENT
INSTRUCTIONS section of de Havilland Service Bulletin (SB) No. 6/
399, Revision E, dated May 25, 1984.
(1) If any crack is found, prior to further flight, accomplish
one of the following:
(i) Replace the cracked part with an airworthy part and
reinspect thereafter at intervals not to exceed 600 hours TIS until
the modification required in paragraph (b) of this AD is
incorporated; or
(ii) Incorporate Modification 6/1769 in accordance with the
ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB No. 6/399,
Revision E, dated May 25, 1984.
Note 1: Modification 6/1769 consists of pulling back the
elevator skins, removing the torque tube assembly, replacing the
root rib assembly and doubler, replacing the second outboard nose
rib, installing a new intercostal, and reinstalling the torque tube
assembly and new skin.
(2) If no cracks are found, reinspect thereafter at intervals
not to exceed 600 hours TIS until the modification required in
paragraph (b) of this AD is incorporated.
(b) Upon the accumulation of 15,000 hours TIS or within the next
100 hours TIS after the effective date of this AD, whichever occurs
later, unless already accomplished in accordance with paragraph
(a)(1)(ii) of this AD, incorporate Modification 6/1769 in accordance
with the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB No.
6/399, Revision E, dated May 25, 1984.
(c) Incorporating Modification 6/1769 as specified in paragraphs
(a)(1)(ii) and (b) of this AD is considered terminating action for
the inspection requirement 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 2: 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.
(g) This amendment supersedes AD 81-10-11, Amendment 39-4112.
Issued in Kansas City, Missouri, on October 25, 1994.
John R. Colomy,
Acting Manager, Small Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-26878 Filed 10-28-94; 8:45 am]
BILLING CODE 4910-13-P
