[Federal Register Volume 60, Number 201 (Wednesday, October 18, 1995)]
[Rules and Regulations]
[Pages 53855-53857]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-25441]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 91-CE-46-AD; Amendment 39-9401; AD 95-21-14]


Airworthiness Directives; de Havilland DHC-6 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes Airworthiness Directive (AD) 83-18-
03, which currently requires repetitively inspecting the tailplane 
outboard hinge assembly on certain de Havilland DHC-6 series airplanes, 
and replacing any cracked tailplane outboard hinge assembly. 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. This action requires eventually modifying 
the tailplane outboard hinge arm and tailplane hinge plate with parts 
of improved design (Modification No. 6/1799) as terminating action for 
the currently required repetitive inspections. The actions specified by 
this AD are intended to prevent tailplane failure caused by cracks in 
either outboard hinge arm or the hinge plate, which, if not detected 
and corrected, could result in loss of control of the airplane.

DATES: Effective December 4, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of December 4, 1995.

ADDRESSES: Service information that applies to this AD may be obtained 
from de Havilland, Inc., 123 Garratt Boulevard, Downsview, Ontario, 
Canada, M3K 1Y5. This information may also be examined at the Federal 
Aviation Administration (FAA), Central Region, Office of the Assistant 
Chief Counsel, Attention: Rules Docket 91-CE-46-AD, Room 1558, 601 E. 
12th Street, Kansas City, Missouri 64106; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, Washington, 
DC.

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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an AD that would apply 
to 

[[Page 53856]]
certain de Havilland DHC-6 series airplanes without Modification No. 6/
1799 incorporated was published in the Federal Register on October 31, 
1994 (59 FR 54410). The action proposed to 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. 6/1799) as terminating action for the 
currently required repetitive inspections. Accomplishment of the 
proposed actions would be in accordance with de Havilland Service 
Bulletin No. 6/421, Revision B, dated November 11, 1983.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were received on the 
proposed rule or the FAA's determination of the cost to the public.
    After careful review of all available information related to the 
subject presented above, the FAA has determined that air safety and the 
public interest require the adoption of the rule as proposed except for 
minor editorial corrections. The FAA has determined that these minor 
corrections will not change the meaning of the AD and will not add any 
additional burden upon the public than was already proposed.
    The FAA estimates that 141 airplanes in the U.S. registry will be 
affected by this AD, that it will take approximately 35 workhours per 
airplane to accomplish the required 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 this 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 required modification.
    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 are affected 
by this 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.
    This AD allows 2,400 hours time-in-service (TIS) after the 
effective date of this AD 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 will have to accomplish the required 
modification within 12 to 24 calendar months after this AD becomes 
effective. For private owners, who typically operate between 100 to 200 
hours TIS per year, this allows 12 to 24 years before the required 
modification is mandatory.
    The following paragraphs present cost scenarios for airplanes where 
no cracks are found and where cracks are found during the inspections, 
and where the remaining airplane life is 15 years with an average 
annual utilization rate of 1,600 hours TIS. A copy of the full Cost 
Analysis and Regulatory Flexibility Determination for this AD 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 will inspect every 
1,200 hours TIS. This amounts 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. This AD requires the same 
1,200-hour TIS inspection until 2,400 hours TIS after the effective 
date of the AD when the operator has to replace the tailplane outboard 
hinge arm assembly (eliminating the need for further repetitive 
inspections), which results in a present value cost of $6,574. The 
incremental cost of this AD for such an airplane is $1,805 
($6,574-$4,769) or $1,309 annualized over the 1.5 years it will 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 will incur a present value incremental cost 
of $3,483 ($5,990-$2,507). This amounts to a per year amount of $1,327 
over the three years it takes 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 finds cracks 
during an inspection will repair the crack prior to further flight and 
resume inspections every 1,200 hours TIS. This AD requires immediate 
replacement of the arm assembly if cracks are found during an 
inspection 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, this AD results in present-day cost savings, which will 
continue to grow over the remaining life of the airplane since 
repetitive inspections are not required. Using the assumed 15-year 
remaining life, the cost savings for incorporating Modification 6/1799 
will 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 could have a 
``significant economic impact on a substantial number of small 
entities,'' and, in cases where they could, 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 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 $5,000 for unscheduled 
operators.
    Of the 141 U.S.-registered airplanes affected by this 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 

[[Page 53857]]
airplanes, one business owns 7 airplanes, one business owns 4 
airplanes, two businesses own 3 airplanes each, thirteen businesses 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 this AD utilizes the 
worst case scenario using the lower annualized cost threshold of $5,000 
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 
will 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, this AD will not have a 
``significant economic impact on a substantial number of small 
entities.''
    The regulations adopted herein will 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 final 
rule does 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) 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 final 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, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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), 40101, 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Airworthiness Directive 
(AD) 83-18-03, Amendment 39-4719, and adding a new AD to read as 
follows:

95-21-14  de Havilland: Amendment 39-9401; 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 do not have Modification 6/1799 incorporated in accordance with 
the Accomplishment Instructions, Replacement, section of de 
Havilland Service Bulletin (SB) No. 6/421, Revision B, dated 
November 11, 1983.

    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 (e) 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 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, which, if not detected and 
corrected, 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 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, 10 Fifth Street, 3rd Floor, 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) The inspections and modification required by this AD shall 
be done in accordance with de Havilland Service Bulletin No. 6/421, 
Revision B, dated November 11, 1983. This incorporation by reference 
was approved by the Director of the Federal Register in accordance 
with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from 
de Havilland, Inc., 123 Garratt Boulevard, Downsview, Ontario M3K 
1Y5 Canada. Copies may be inspected at the FAA, Central Region, 
Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th 
Street, Kansas City, Missouri, or at the Office of the Federal 
Register, 800 North Capitol Street, NW., 7th Floor, suite 700, 
Washington, DC.
    (g) This amendment (39-9401) supersedes AD 83-18-03, Amendment 
39-4719.
    (h) This amendment (39-9401) becomes effective on December 4, 
1995.

    Issued in Kansas City, Missouri, on October 6, 1995.
Henry A. Armstrong,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-25441 Filed 10-17-95; 8:45 am]
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