[Federal Register Volume 59, Number 28 (Thursday, February 10, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-3048]


[[Page Unknown]]

[Federal Register: February 10, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 91-CE-88-AD; Amendment 39-8819; AD 94-04-01]

 

Airworthiness Directives: de Havilland DHC-6 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes two existing airworthiness 
directives (AD's) that currently require repetitively inspecting the 
wing attachment fittings and the wing front fittings 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 repetitions of certain short-interval inspections when 
improved parts or modifications are available. This action requires 
incorporating a modification that would eliminate the need for the 
repetitive inspections currently required by the two existing AD's. The 
actions specified by this AD are intended to prevent loss of control of 
the airplane caused by cracked wing attachment fittings.

DATES: Effective March 31, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 31, 1994.

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, 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, 181 South Franklin Avenue, Room 
202, Valley Stream, New York 11581; telephone (516) 791-6220.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations to include an AD that would apply to certain de 
Havilland DHC-6 series airplanes was published in the Federal Register 
on October 27, 1993 (58 FR 57758). The action proposed to supersede AD 
69-02-01 and AD 85-16-10 with a new AD that would (1) initially retain 
the repetitive inspection of the wing attachment fittings required by 
the current AD's; and (2) eventually require installing new steel 
adapter fittings as terminating action for those repetitive 
inspections. The inspections would be accomplished in accordance with 
de Havilland Service Bulletin (SB) No. 6/476, Revision B, dated January 
22, 1988, and the installation would be accomplished in accordance with 
de Havilland SB No. 6/500, dated January 22, 1988.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. One comment was received supporting 
the proposed rule and no comments were received on the FAA's 
determination of the cost to the public.
    After careful review of all available 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 nor 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 96 workhours per 
airplane to accomplish the required action, and that the average labor 
rate is approximately $55 an hour. Parts cost approximately $6,750 per 
airplane. Based on these figures, the total cost impact of this AD on 
U.S. operators is estimated to be $2,033,072.
    AD 69-02-01 and AD 85-16-10, both of which are superseded by this 
action, currently require inspecting the top inner faces of the wing 
attachment fittings for cracks at intervals of 500 hours time-in-
service (TIS), but require removing both the left and right upper wing- 
fuselage fairings, dye penetrant inspecting them utilizing a 10-power 
glass, and reattaching the fairings. These inspections take 
approximately 3 workhours at an average cost of $55 per hour; 
approximately $165 per airplane or $297,440 for the entire fleet. The 
inspection procedures of this AD take approximately 3 workhours at an 
average cost of $55 per hour.
    The cost figures do not account for the recurring costs of the 
repetitive inspections required by AD 69-02-01 and AD 85-16-10. This AD 
only requires these repetitive inspections until accomplishment of the 
mandatory modification. This elimination of the repetitive inspections 
reduces the cost of the required modification requirement.
    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 are affected 
by this 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.
    This AD allows 2,000 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 required modification within 10 to 20 
calendar months after this AD becomes effective. For private owners, 
who typically operate between 100 to 200 hours TIS per year, this will 
allow 120 to 240 calendar months (about 10 to 20 years) before the 
required modification is mandatory. In addition, replacing the fittings 
terminates the need for the repetitive inspections.
    The incremental costs of this AD depend on the utilization of de 
Havilland DHC-6 series airplanes, and whether cracks were found during 
any of the repetitive inspections accomplished within 2,000 hours TIS 
after the effective date of this AD. The discussion that follows 
assumes that no cracked fittings are found and operators/owners do not 
replace the fittings until required at 2,000 hours TIS after the 
effective date of this AD.
    This AD imposes additional costs on most operators/owners of de 
Havilland DHC-6 series airplanes. Although the action eliminates the 
repetitive inspections upon replacement of the fitting at 2,000 hours 
TIS after the effective date of the AD, the cost of the replacement 
fittings will most likely be more than the cost of the repetitive 
inspections. The following presents the greatest present value 
incremental costs for 10, 20, and 30-year remaining service lives (a 
chart that represents this is contained in the regulatory flexibility 
analysis and may be obtained by contacting the Docket at the location 
contained in the ADDRESSES section of the preamble of this AD):

     10-year remaining service life--Approximately $9,000 
for de Havilland DHC-6 series airplanes utilized an average of 725 
hours TIS annually;
     20-year remaining service life--Approximately $8,200 
for de Havilland DHC-6 series airplanes utilized an average of 560 
hours TIS annually; and
     30-year remaining service life--Approximately $7,800 
for de Havilland DHC-6 series airplanes utilized an average of 525 
hours annually.

    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 required 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 9 aircraft owned and annualized 
cost threshold at $65,300 for scheduled operators and $4,600 for 
unscheduled operators (expressed in second quarter 1993 dollars).
    The 169 U.S.-registered airplanes affected by this 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 their de 
Havilland DHC-6 series airplanes in scheduled service. According to 
statistics obtained by the FAA, these airplane operators in scheduled 
service utilize their 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 solicited 
comments concerning the impact of the notice of proposed rulemaking 
(NPRM) on owners of affected airplanes, and received no comments on 
this matter. Based on the possibility that this AD could have a 
significant impact on a substantial number of small entities, 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 significant under DOT Regulatory Policies and Procedures (44 FR 
11034, February 26, 1979) because of substantial public interest; 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 14 CFR part 
39 of the Federal Aviation Regulations 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 69-02-01, Amendment 39-
2347, and AD 85-16-10, Amendment 39-5216, and adding the following new 
AD to read as follows:

94-04-01 De Havilland: Amendment 39-8819; Docket No. 91-CE-88-AD. 
Supersedes AD 69-02-01, Amendment 39-2347, and AD 85-16-10, 
Amendment 39-5216.

    Applicability: Models DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-
300 airplanes (all serial numbers), certificated in any category.
    Compliance: Required as indicated, unless already accomplished.
    To prevent loss of control of the airplane caused by cracked 
wing attachment fittings, accomplish the following:
    (a) Within the next 100 hours time-in-service (TIS) after the 
effective date of this AD, unless already accomplished within the 
last 400 hours TIS, and thereafter at intervals not to exceed 500 
hours TIS until compliance with paragraph (b) or (c) of this AD, 
accomplish the following:
    (1) Remove both left and right upper wing-fuselage fairings in 
accordance with the applicable de Havilland maintenance manual.
    (2) Using dye penetrant procedures and at least 10-power 
magnification, visually inspect the top inner faces of the left and 
right forward wing attachment fittings, either part number (P/N) 
C6WM1031-1 and C6WM1031-2, P/N C6WM1133-1 and C6WM1133-2, or P/N 
C6WM1162-1 and C6WM1162-2, for cracks in accordance with the 
Accomplishment Instructions section of de Havilland Service Bulletin 
(SB) No. 6/476, Revision B, dated January 22, 1988.
    (b) If cracks are found, prior to further flight, replace the 
forward wing attachment fittings with new front steel adapter 
fittings (Modification No. 6/1887), P/N C6WM1162-3 and C6WM1163-4, 
in accordance with the Accomplishment Instructions section of de 
Havilland SB No. 6/500, dated January 22, 1988.
    (c) Within the next 2,000 hours TIS after the effective date of 
this AD, unless already accomplished in accordance with paragraph 
(b) of this AD, replace the forward wing attachment fittings with 
new front steel adapter fittings (Modification No. 6/1887), P/N 
C6WM1162-3 and C6WM1163-4, in accordance with the Accomplishment 
Instructions section of de Havilland SB No. 6/500, dated January 22, 
1988.
    (d) The installation of new front steel adapter fittings 
(Modification No. 6.1887) as specified in paragraphs (b) and (c) of 
this AD is considered terminating action for the repetitive 
inspection requirement of this AD.
    (e) Special flight permits may be issued in accordance with 14 
CFR 21.197 and 21.199 to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (f) An alternative method of compliance or adjustment of the 
compliance times that provides an equivalent level of safety may be 
approved by the Manager, New York Aircraft Certification Office, 181 
Franklin Avenue, room 202, 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 Aircraft 
Certification Office.

    Note: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the New York Aircraft Certification Office.

    (g) The inspections required by this AD shall be done in 
accordance with de Havilland Service Bulletin No. 6/476, Revision B, 
dated January 22, 1988. The modification required by this AD shall 
be done in accordance with de Havilland Service Bulletin No. 6/500, 
dated January 22, 1988. 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, Canada, M3K 1Y5. 
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., suite 700, Washington, DC.
    (h) This amendment (39-8819) supersedes AD 69-02-01, Amendment 
39-2347, and AD 85-16-10, Amendment 39-5216.
    (i) This amendment (39-8819) becomes effective on March 31, 
1994.

    Issued in Kansas City, Missouri, on February 3, 1994.
Barry D. Clements,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 94-3048 Filed 2-9-94; 8:45 am]
BILLING CODE 4910-13-U