[Federal Register Volume 60, Number 178 (Thursday, September 14, 1995)]
[Rules and Regulations]
[Pages 47685-47687]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-21960]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 91-CE-22-AD; Amendment 39-9357; AD 95-18-10]


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) 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. This action requires 
modifying the elevator root rib as terminating action for the 
repetitive inspections currently required by AD 81-10-11. The actions 
specified by this AD are intended to prevent failure of the elevator 
root rib, which could result in loss of control of the airplane.

DATES: Effective October 26, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 26, 1995.

ADDRESSES: Service information that applies to this AD may be obtained 
from de Havilland, Inc., 123 Garratt Boulevard, Downsview, Ontario, 
Canada, M3K1Y5. 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-22-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 de Havilland DHC-6 series airplanes that do not have Modification 
No. 6/1769 incorporated was published in the Federal Register on 
October 3, 1994 (59 FR 54412). The action proposed to 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. 
Accomplishment of the proposed actions would be in accordance with de 
Havilland Service Bulletin No. 6/399, Revision E, dated May 25, 1984.
    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 including the referenced service information, 
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 169 airplanes in the U.S. registry will be 
affected by this AD, that it will take approximately 54 workhours per 
airplane to accomplish the required 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 this AD on 
U.S. operators is estimated to be $1,257,360. This figure is based on 
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 will be 
affected by this 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 time-in-service (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 those 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 this 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 will 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 this AD over that required by AD 81-
10-11 is $5,919 for an airplane utilized 

[[Page 47686]]
in scheduled service, and $6,642 for an airplane utilized in general 
aviation.
     No Cracks Scenario for Model DHC-6-300 Airplanes: These 
airplanes will 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 this AD over that required by AD 81-10-11 is 
$4,962 for an airplane utilized in scheduled 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 will 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 169 U.S.-registered airplanes affected by this AD, six 
airplanes are owned by the federal government. Of the other 163 
airplanes, 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 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, this 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 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) 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 
action 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 required action is the best course to 
achieve the safety objective of returning the airplane to its original 
certification level of safety.

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) 81-10-11, Amendment 39-4112, and adding a new AD to read as 
follows:

95-18-10  De Havilland: Amendment 39-9357; 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.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability revision, 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 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 2: 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 

[[Page 47687]]
later, unless already accomplished, 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 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 3: 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. 6/399, 
Revision E, dated May 25, 1984. 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 (39-9357) supersedes AD 81-10-11, Amendment 
39-4112.
    (h) This amendment (39-9357) becomes effective on October 26, 
1995.

    Issued in Kansas City, Missouri, on August 28, 1995.
Henry A. Armstrong,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-21960 Filed 9-13-95; 8:45 am]
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