[Federal Register Volume 62, Number 62 (Tuesday, April 1, 1997)]
[Proposed Rules]
[Pages 15443-15446]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-8252]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 91-CE-87-AD]
RIN 2120-AA64
Airworthiness Directives; De Havilland DHC-6 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Supplemental notice of proposed rulemaking (NPRM); Reopening of
the comment period.
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SUMMARY: This document proposes to revise an earlier proposed
airworthiness directive (AD), which would have superseded AD 80-13-11
R2. That AD currently requires repetitively inspecting the elevator,
flap, aileron, and rudder control rods for cracks on certain de
Havilland DHC-6 series airplanes, replacing any cracked rod, and
installing rod sleeves. The previous document would have required
replacing the elevator trim and elevator/flap interconnect rods, the
aileron control rods, the elevator control rods, and the rudder control
rods with parts of improved design, and repetitively inspecting these
rods thereafter at certain intervals. These replacements would reduce
the need for the number of repetitions of the inspections currently
required by AD 80-13-11 R2. The Federal Aviation Administration (FAA)
has determined that the flap control rods should also be replaced with
parts of improved design as terminating action for repetitive
inspections currently required by AD 80-03-08. The proposed action
would supersede both AD 80-13-11 R2 and AD 80-03-08 and would require
the replacements as terminating action to the repetitive inspections
currently required. The proposed action is part of the FAA's policy on
commuter class aircraft, which briefly states that, when a modification
exists that could eliminate or reduce the number of required critical
inspections, the modification should be incorporated. The actions
specified by the proposed AD are intended to prevent cracking of these
control rods, which, if not detected and corrected, could result in
loss of control of the airplane.
DATES: Comments must be received on or before June 13, 1997.
ADDRESSES: Submit comments in triplicate to the FAA, Central Region,
Office of the Assistant Chief Counsel, Attention: Rules Docket No. 91-
CE-87-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, 10 Fifth Street, 3rd Floor,
Valley Stream, New York 11581; telephone (516) 256-7523; facsimile
(516) 568-2716.
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-87-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of Supplemental NPRM
Any person may obtain a copy of this supplemental NPRM by
submitting a request to the FAA, Central Region, Office of the
Assistant Chief Counsel, Attention: Rules Docket No. 91-CE-87-AD, Room
1558, 601 E. 12th Street, Kansas City, Missouri 64106.
Discussion
A proposal to amend part 39 of the Federal Aviation Regulations (14
CFR part 39) to include an AD that would apply to certain de Havilland
DHC-6 series airplanes was published in the Federal Register as a
notice of proposed rulemaking (NPRM) on October 12, 1993 (58 FR 52714).
The NPRM proposed to supersede AD 80-13-11 R2 with a new AD that would
(1) require replacing elevator trim and elevator/flap interconnect
rods, and the flap, aileron, elevator, and rudder control rods with
parts of improved design; and (2) retain the aileron control rod
inspections currently required by AD 80-13-11 R2, but reduce the number
of repetitions of these inspections. Accomplishment of the proposed
replacement as specified in the NPRM would be in accordance with de
Havilland Service Bulletin (SB) No. 6/502, dated March 24, 1989.
Accomplishment of the proposed inspections as specified in the NPRM
would be in accordance with de Havilland SB No. 6/390, Revision E,
dated December 20, 1991.
Interested persons have been afforded an opportunity to participate
in the making of this AD. No comments were received on the NPRM or on
the FAA's determination of the cost on the public.
The FAA's Aging Commuter-Class Aircraft Policy
The actions specified in the NPRM are part of the FAA's aging
commuter class aircraft policy, which briefly states that, when a
modification exists that could eliminate or reduce the number of
required critical inspections, the modification should be incorporated.
This policy is based on the FAA's determination that reliance on
critical repetitive inspections on aging commuter-class airplanes
carries an unnecessary safety risk when a design
[[Page 15444]]
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.
Events Leading to the Issuance of This Supplemental NPRM
Since issuing the NPRM, the FAA has determined that AD 80-03-08 is
also one that should be superseded by this action to coincide with the
FAA's aging commuter aircraft policy. AD 80-03-08 currently requires
repetitively inspecting the flap control rods on de Havilland DHC-6
series airplanes. De Havilland SB No. 6/502 also specifies procedures
for replacing the flap control rods with parts of improved design. The
FAA has determined that when these replacements are incorporated, the
number of repetitive inspections of these control rods can be reduced.
After reviewing all information related to the events leading to
this supplemental NPRM, the FAA has determined that (1) the flap
control rod replacements should be added to the document; and (2) AD
action should be taken to prevent cracking of the elevator trim and
elevator/flap interconnect rods, the aileron control rods, the elevator
control rods, the rudder control rods, and the flap control rods. If
not detected and corrected, a cracked control rod could result in loss
of control of the airplane.
Explanation of the Provisions of the Proposed AD
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 both AD 80-13-11 R2
and AD 80-03-08 with a new AD that would (1) require replacing
elevator, flap, aileron, and rudder control rods and elevator trim and
elevator flap/interconnect control rods with improved parts; and (2)
retain the aileron control rod inspections currently required by AD 80-
13-11 R2, but reduce the number of repetitions of these inspections.
Accomplishment of the proposed replacements would be in accordance with
de Havilland SB No. 6/502, dated March 24, 1989. Accomplishment of the
proposed inspections would be in accordance with de Havilland SB No. 6/
390, Revision E, dated December 20, 1991, and de Havilland SB No. 6/
388, Revision C, dated October 29, 1982.
The FAA prepared a Regulatory Flexibility Determination and
Analysis for the original proposal. This analysis was based on all
owners/operators of de Havilland DHC-6 airplanes replacing all control
rods specified in de Havilland SB No. 6/502. Because the replacement
flap control rods that the FAA is adding to the proposal are already
included in de Havilland SB No. 6/502, there is no need to accomplish a
separate Regulatory Flexibility Determination and Analysis. The FAA is
reprinting the synopsis of this analysis in this document.
Cost Impact
The FAA estimates that 169 airplanes in the U.S. registry would be
affected by the proposed AD, that it would take approximately 20
workhours (4 workhours/ inspection and 16 workhours/replacement) per
airplane to accomplish the proposed action, and that the average labor
rate is approximately $60 an hour. Parts cost approximately $15,600 per
airplane. Based on these figures, the total cost impact of the proposed
AD on U.S. operators is estimated to be $2,839,200.
AD 80-13-11 R2 and AD 80-03-08, which would both be superseded by
the proposed action, currently require inspecting these control rod
assemblies. These inspections take approximately 32 workhours at an
average cost of $60 per hour; approximately $1,920 per airplane or
$324,480 for the entire fleet. The inspection procedures of the
proposed AD would be less costly and less frequent than those required
by AD 80-13-11 R2 and AD 80-03-08.
With the above figures in mind, including the costs for the
modification proposed by this action, the proposed AD would cost an
additional $14,880 per airplane over that already required by AD 80-13-
11 R2 and AD 80-03-08, or a total additional fleet cost of $2,524,860.
These figures do not account for the recurring costs through the
repetitive inspection requirement of AD 80-13-11 R2 and AD 80-03-08,
and the proposed AD. The proposed AD would only require repetitive
inspections every 2,400 hours time-in-service (TIS) after the control
rod assembly is replaced, where AD 80-13-11 R2 currently requires
repetitive inspections every 800 hours TIS and AD 80-03-08 requires
repetitive inspections every 200 hours TIS.
The incremental costs of the proposed AD would depend on the
remaining service life of a DHC-6 airplane and its utilization, i.e.,
the number of hours TIS per year. The proposed AD would provide a cost
savings over that already required to most owner/operators of de
Havilland DHC-6 airplanes. The following examines the incremental costs
to owners of de Havilland DHC-6 series airplanes with remaining service
lives of 10, 20, and 30 years if the airplanes are utilized between 100
and 2,500 hours TIS annually.
The proposed AD would provide a cost savings at a service life of
10 years for operators utilizing their airplanes less than 135 hours
TIS or more than 1,000 hours TIS annually, and would provide a cost
savings at service lives of 20 and 30 years for all de Havilland DHC-6
series airplanes, regardless of airplane usage. The savings resulting
from the less frequent inspections more than offset the costs of
replacing the control rods. The cost savings would be at least $2,800
at an average 20-year remaining service life and utilizing a 7 percent
interest rate. For a 30-year remaining service life, the operator
should realize a cost savings of at least $6,000 (with a 7 percent
interest rate).
De Havilland DHC-6 series airplanes that are utilized between 135
and 1,000 hours TIS annually may not see a cost savings when replacing
the control rods based upon a 10-year remaining service life. Before
issuing this supplemental notice of proposed rulemaking, the FAA took
into account that the costs of replacing the rods could be greater than
the savings from the inspections required by the proposed AD for
operators utilizing their airplanes within this range.
The Proposed AD's Impact Utilizing the FAA's Aging Commuter Class
Aircraft Policy
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 by 14 different
operators. A significant number of the remaining 50 percent are
operated in other forms of air transportation such as air cargo and air
taxi.
The proposed AD allows 500 hours time-in-service (TIS) before
accomplishment of the design modification would become mandatory. The
average utilization of the fleet for those airplanes in commercial
commuter service is approximately 25 to 50 hours TIS per week. Based on
[[Page 15445]]
these figures, operators of commuter-class airplanes involved in
commercial operation would have to accomplish the proposed modification
within two to five calendar months after the proposed AD would become
effective. Based on these scheduled operation figures, repetitive
inspections for the proposed AD for operators who had accomplished the
modification would be required approximately every one to two years.
For private owners, who typically operate between 100 to 200 hours TIS
per year, this would allow two to five years before the proposed
modification would be mandatory. Based on these nonscheduled operation
figures, repetitive inspections for the proposed AD for operators who
had accomplished the modification would be required approximately every
12 to 24 years.
Regulatory Flexibility Determination and Analysis
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 the proposed rule, or any
number of small entities subject to the rule which is substantial in
the judgment of the rulemaking official. A ``significant economic
impact'' is defined as 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 nine aircraft owned and the
annualized cost threshold at $65,300 for scheduled operators and $5,000
for unscheduled operators.
The 169 U.S.-registered airplanes affected by the proposed AD are
owned according to the following breakdown: 13 by individuals, 8 by
U.S. government agencies, and 148 by businesses or not-for-profit
enterprises. Of the 148 entities, one owns 26 airplanes, one owns 11
airplanes, nineteen own between 2 and 9 airplanes, and fifty own 1
airplane each.
The FAA cannot determine the sizes of all the 148 owner entities
nor the relative significance of the costs or cost savings estimated
above. However, more than one-third of these entities operate de
Havilland DHC-6 series airplanes in scheduled service. According to
statistics obtained by the FAA, these airplane operators in scheduled
service utilize the affected airplanes an average of 1,383 hours TIS
annually, and general aviation operators utilize their airplanes an
average of 706 hours TIS annually. These figures may have a standard of
error of 14.4 percent and the general aviation average may include some
airplanes in commuter service. The FAA cannot reasonably estimate the
distribution of these hours among the de Havilland DHC-6 fleet.
Because of these uncertainties, no cost thresholds for significant
economic impact can be reasonably determined. The FAA solicits comments
concerning the impact of this proposed AD on small entity owners of the
affected airplanes. Based on the possibility that this proposed AD
could have a significant impact on a substantial number of small
entities, the FAA conducted a Regulatory Flexibility Determination and
Analysis. A copy of this analysis may be obtained by contacting the
Rules Docket at the location provided under the caption ADDRESSES.
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 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 USC 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing both AD 80-13-11 R2,
Amendment 39-4703, and AD 80-03-08, Amendment 39-3682, and by adding
the following new AD:
De Havilland: Docket No. 91-CE-87-AD. Supersedes AD 80-13-11 R2,
Amendment 39-4703, and AD 80-03-08, Amendment 39-3682.
Applicability: Models DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-
300 airplanes (all serial numbers), certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must request approval for an
alternative method of compliance in accordance with paragraph (d) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not been
eliminated, the request should include specific proposed actions to
address it.
Compliance: Required as indicated, unless already accomplished.
To prevent loss of control of the airplane caused by cracked
elevator, flap, aileron, elevator trim, elevator/flap interconnect,
and rudder control rods, accomplish the following:
(a) Within the next 500 hours time-in-service
(TIS) after the effective date of this AD, replace the following
2024-T3 or 2024-T81 control rods with 6061-T6 control rods in
accordance with the ACCOMPLISHMENT INSTRUCTIONS section of de
Havilland Service Bulletin (SB) No. 6/502, dated March 24, 1989:
(1) Flap Control Rods: Modification No. 6/1781;
[[Page 15446]]
(2) Elevator Trim and Elevator/Flap Interconnect Control Rods:
Modification No. 6/1785;
(3) Aileron Control Rods: Modification No. 6/1791;
(4) Elevator Control Rods: Modification No. 6/1792; and
(5) Rudder Control Rods; Modification No. 6/1802.
Note 2: The specific part numbers of the 2024-T3 or 2024-T81
control and interconnect control rods and their 6061-T6 replacement
part numbers are contained in de Havilland SB No. 6/502, dated March
24, 1989.
(b) Within 2,400 hours TIS after the replacement required by
paragraph (a) of this AD, and thereafter at intervals not to exceed
2,400 hours TIS, inspect all the affected control rods for cracks in
accordance with the ACCOMPLISHMENT INSTRUCTIONS section of de
Havilland SB No. 6/390, Revision E, dated December 20, 1991; or de
Havilland SB No. 6/388, Revision C, dated October 29, 1982, as
applicable. Prior to further flight, replace any cracked rod with a
new 6061-T6 rod as specified in and in accordance with the
ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB No. 6/502,
dated March 24, 1989.
(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.
(d) An alternative method of compliance or adjustment of the
compliance time that provides an equivalent level of safety may be
approved by the Manager, New York Aircraft Certification Office
(ACO), 10 Fifth Street, 3rd Floor, Valley Stream, New York 11581.
The request shall be forwarded through an FAA Maintenance Inspector,
who may add comments and then send it to the Manager, New York ACO.
Note 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the New York ACO.
(e) All persons affected by this directive may obtain copies of
the documents referred to herein upon request to de Havilland, Inc.,
123 Garratt Boulevard, Downsview, Ontario, Canada, M3K 1Y5; or may
examine these documents at the FAA, Central Region, Office of the
Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City,
Missouri 64106.
(f) This amendment supersedes AD 80-13-11 R2, Amendment 39-4703,
and AD 80-03-08, Amendment 39-3682.
Issued in Kansas City, Missouri, on March 26, 1997.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 97-8252 Filed 3-31-97; 8:45 am]
BILLING CODE 4910-13-U
