[Federal Register Volume 60, Number 178 (Thursday, September 14, 1995)]
[Rules and Regulations]
[Pages 47679-47682]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-21957]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 91-CE-21-AD; Amendment 39-9358; AD 95-18-11]
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) 73-05-
03, which currently requires repetitively inspecting the rear spar cap
for cracks on certain de Havilland DHC-6 series airplanes, and
replacing any cracked rear spar cap. 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 wing
rear spar support (Modification No. 6/1301) as terminating action for
the currently required repetitive inspections. The actions specified by
this AD are intended to prevent cracking of the top flange of the wing
spar attachment caps, which, if not detected and corrected, 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, 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-21-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 certain de Havilland DHC-6 series airplanes without Modification No.
6/1301 incorporated was published in the Federal Register on October
31, 1994 (59 FR 54415). The action proposed to supersede AD 73-05-03
with a new AD that would (1) initially retain the requirement of
repetitively inspecting the wing rear spar cap for cracks and replacing
any cracked part; and (2) eventually require installing wing rear spar
attachment caps that are manufactured from a material having improved
stress corrosion resistant properties (Modification 6/1301) as
terminating action for the repetitive inspections. Accomplishment of
the proposed actions would be in accordance with de Havilland Service
Bulletin No. 6/295, Revision D, dated December 20, 1991.
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
[[Page 47680]]
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 82 airplanes in the U.S. registry will be
affected by this AD, that it will take approximately 22 workhours per
airplane to accomplish the required modification, and that the average
labor rate is approximately $60 an hour. Parts cost approximately
$6,350 per airplane. Based on these figures, the total cost impact of
this AD on U.S. operators is estimated to be $628,940. This figure is
based upon the assumption that no affected airplane owner/operator has
incorporated Modification 6/1301.
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 82 airplanes in the U.S. registry that will be
affected by this AD, the FAA has determined that approximately 45
percent are operated in scheduled passenger service. A significant
number of the remaining 55 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 certain category cracks were found
during the inspections, and where the remaining airplane life is 15
years with an average annual utilization rate of 1,600 hours time-in-
service (TIS). A copy of the full Cost Analysis and Regulatory
Flexibility Determination for the required action may be examined at
the FAA, Central Region, Office of the Assistant Chief Counsel,
Attention: Rules Docket No. 91-CE-21-AD, Room 1558, 601 E. 12th Street,
Kansas City, Missouri.
No Cracks Scenario: Under the provisions of AD 73-05-03,
an owner/operator of an affected de Havilland DHC-6 series airplane in
scheduled service who operates an average of 1,600 hours TIS annually
will inspect every 26 weeks. This amounts to a remaining airplane life
(estimated 15 years) cost of $14,058; this figure is based on the
assumption that no cracks are found during the inspections. This AD
will incur the inspection at one 1,200-hour TIS interval and then, at
2,400 hours TIS after the effective date of the AD, the operator has to
replace the top flange of the wing spar attachment caps (eliminating
the need for further repetitive inspections). This results in a present
value cost of $8,331, which is a present value cost savings over that
required in AD 73-05-03 of $5,727 or $4,154 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 inspection will incur a present
value cost savings over that required in AD 73-05-03 of $6,430. This
amounts to a per year savings of $2,450 over the 1.5 years it takes to
accumulate 2,400 hours TIS.
Category I cracks found scenario: These are spanwise
cracks that are inboard of the third rivet, or spanwise cracks that
exceed 50 inches, or any chordwise cracks. Under the provisions of AD
73-05-03, an owner/operator who finds cracks during an inspection under
this scenario has to immediately repair the cracked part and
repetitively inspect every 26 weeks. This AD will require immediate
replacement as terminating action for the repetitive inspections, which
results in present value compliance costs of $8,355. The present value
cost savings over that required in AD 73-05-03 for this scenario is
$6,300 for airplanes in scheduled service and $6,295 per general
aviation airplane.
Category II cracks found scenario: These are spanwise
cracks that are outboard of the 10th rivet and within the limits of
paragraph (b) of the service bulletin. Under the provisions of AD 73-
05-03, an owner/operator who finds cracks during an inspection under
this scenario has to repetitively inspect every 13 weeks. This results
in present value compliance costs of $27,625. This AD would require
repetitive inspections every 600 hours TIS until replacement of the top
flange of the wing rear spar attachment caps at 2,400 hours TIS after
the effective date of the AD as terminating action for the repetitive
inspections. This results in present value compliance costs of $9,700.
Immediate replacement of the top flange is more economical than
repetitively inspecting; present value costs are $8,355. The present
value cost savings over that required in AD 73-05-03 for this scenario
is $19,272 per airplane in scheduled service and $19,269 per general
aviation airplane.
Category III cracks found scenario: These are spanwise
cracks that are outboard of the 10th rivet and within the limits of
paragraph (c) of the service bulletin. Under the provisions of AD 73-
05-03, an owner/operator who finds cracks during an inspection in this
scenario has to repetitively inspect every 2 weeks. This results in
present value compliance costs of $175,000. This AD requires repetitive
inspections every 100 hours TIS until replacement of the top flange of
the wing rear spar attachment caps at 2,400 hours TIS after the
effective date of the AD as terminating action for the repetitive
inspections. This results in present value compliance costs of $13,965.
Immediate replacement of the top flange is more economical than
repetitively inspecting; present value costs are $8,355. The present
value cost savings over that required in AD 73-05-03 for this scenario
is $166,075 per airplane in scheduled service and $166,784 per general
aviation airplane.
Category IV cracks found scenario: These are spanwise
cracks that are outboard of the 10th rivet and exceed the limits of
paragraph (b) or (c) of the service bulletin. Also included are cracks
in the splice plates of the vertical and horizontal legs of the rear
spar or elongated rivet holes. Under the provisions of AD 73-05-03, an
owner/operator who finds cracks during an inspection under this
scenario has to immediately repair any crack and then repetitively
inspect every 26 weeks. This results in present value costs of $14,500.
This AD requires immediate crack repair, then an inspection after
accumulating 1,200 hours TIS, and replacement of the top flange of the
wing rear spar attachment caps at 2,400 hours TIS after the effective
date of the AD as terminating action for the repetitive inspections.
This results in present value compliance costs of $8,929. Immediate
replacement of the top flange is more economical than repetitively
inspecting; present value costs are $8,355. The present value cost
savings over that required in AD 73-05-03 for this scenario is $6,040
per airplane in scheduled service and $6,430 per general aviation
airplane.
Category V cracks found scenario: These are spanwise
cracks that are between the third and tenth rivet. Under the provisions
of AD 73-05-03, an owner/operator who finds cracks during an inspection
under this scenario has to immediately repair any crack, repetitively
inspect every 2 weeks, replace the top flange of the wing rear spar
attachment caps, and repetitively inspect thereafter every 26 weeks.
This results in present value compliance costs of about $30,000. This
AD requires immediate crack repair, repetitive inspections every 50
hours TIS, and replacement of the top flange of the wing rear spar
attachment caps at 2,400 hours TIS after the effective date of the AD
as terminating action for the repetitive inspections. This results in
present value compliance costs of
[[Page 47681]]
$38,988. Immediate replacement of the top flange is more economical
than repetitively inspecting; present value costs are $8,355. The
present value cost savings over that required in AD 73-05-03 for this
scenario are $19,356 per airplane in scheduled service and $26,367 per
general aviation airplane.
Category VI cracks found scenario: These are spanwise
cracks that have a total length exceeding 30 inches but not exceeding
50 inches. Under the provisions of AD 73-05-03, an owner/operator who
finds cracks during an inspection under this scenario has to
immediately repair any crack, replace the top flange of the wing rear
spar attachment caps at 26 weeks, and repetitively inspect thereafter
every 26 weeks. This results in present value compliance costs of about
$21,200. This AD requires immediate crack repair, repetitive
inspections every 600 hours TIS, and replacement of the top flange of
the wing rear spar attachment caps at 2,400 hours TIS after the
effective date of the AD as terminating action for the repetitive
inspections. This results in present value compliance costs of $10,289.
Immediate replacement of the top flange is more economical than
repetitively inspecting; present value costs are $8,355. The present
value cost savings over that required in AD 73-05-03 for this scenario
is $12,707 per airplane in scheduled service and $13,028 per general
aviation airplane.
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 82 U.S.-registered airplanes affected by this AD, three
airplanes are owned by the federal government. Of the other 79, one
business owns 24 airplanes, one business owns 7 airplanes, one business
owns 6 airplanes, one business owns 3 airplanes, 6 businesses own 2
airplanes each, and twenty-seven businesses own 1 airplane each.
As presented in the crack scenario discussion, replacing the top
flange of the wing rear spar attachment caps immediately or within
2,400 hours TIS after the effective date of this AD is more economical
in all scenarios than continuing to repetitively inspect the part for
the life of the airplane. Therefore, 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 U.S.C. 106(g), 40101, 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing Airworthiness Directive
(AD) 73-05-03, Amendment 39-1658, and adding a new AD to read as
follows:
95-18-11 De Havillland: Amendment 39-9358; Docket No. 91-CE-21-AD.
Supersedes AD 73-05-03, Amendment 39-1658.
Applicability: Models DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-
300 airplanes (serial numbers 1 to 330), certificated in any
category, that have not incorporated Modification 6/1301 in
accordance with the instructions in Part C of de Havilland Service
Bulletin (SB) 6/295, Revision D, dated December 20, 1991.
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 (f) 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 cracking of the top flange of the wing rear spar
attachment caps, which, if not detected and corrected, could result
in loss of control of the airplane, accomplish the following:
(a) Within the next 100 hours time-in-service (TIS) after the
effective date of this AD, inspect both wing rear spar attachment
caps, part number (P/N) C6WM1032, for cracks in accordance with
paragraph A of the Accomplishment Instructions section of de
Havilland SB No. 6/295, Revision D, dated December 20, 1991. The
exposure time of Inspection Method A.1 (Radiographic) in this
service bulletin shall be 120 seconds instead of 60 seconds for the
inboard X-ray tube location, and the X-ray beam angle shall be
decreased from 10 degrees to 5 degrees for all X-ray tube locations.
(1) If cracking is not detected, reinspect each cap every 1,200
hours TIS until a Modification 6/1301 spar cap is installed as
required by paragraph (c) of this AD.
(2) If spanwise cracking is detected outboard of the 10th rivet,
accomplish the following:
[[Page 47682]]
(i) For cracks that have the following (the criteria of
paragraph (c) in the Compliance section of de Havilland SB No. 6/
295, Revision D, dated December 20, 1991):
First to tenth rivet............. No cracks.
11th to 29th rivet............... One cracked pitch (the distance
between adjacent rivet holes) in ten
pitches with four uncracked pitches
minimum between cracks.
30th to 69th rivet............... Two cracked pitches in ten pitches
with four uncracked pitches minimum
between cracks.
70th to 74th (end)............... One cracked pitch.
Repeat the inspection specified in paragraph (a) of this AD at
intervals not to exceed 100 hours TIS until a Modification 6/1301
spar cap is installed as required by paragraph (c) of this AD.
(ii) For cracks found outboard of the 10th rivet that run only
between two adjacent rivets provided not more than four such cracks
exist in an attachment cap and a minimum of two rivet pitch lengths
of uncracked material separate cracks (the criteria of paragraph (b)
in the Compliance section of de Havilland SB No. 6/295), repeat the
inspection specified in paragraph (a) of this AD at intervals not to
exceed 600 hours TIS until a Modification 6/1301 spar cap is
installed as required by paragraph (c) of this AD.
(iii) For cracks that meet or exceed the criteria of paragraphs
(b) or (c) in the Compliance section of de Havilland SB No. 6/295,
prior to further flight, reinforce the spar cap in accordance with
paragraph B of the Accomplishment Instructions section of de
Havilland SB No. 6/295, Revision D, dated December 20, 1991, and
repeat the inspection specified in paragraph (a) of this AD at
intervals not to exceed 1,200 hours TIS until a Modification 6/1301
spar cap is installed as required by paragraph (c) of this AD.
(3) If spanwise cracking is detected inboard of the third rivet,
or if a chordwise crack is detected, or if the total length of
cracks on a cap exceeds 50 inches, prior to further flight, replace
the spar cap with a Modification 6/1301 cap in accordance with
paragraph C of the Accomplishment Instructions section of de
Havilland SB No. 6/295, Revision D, dated December 20, 1991.
(4) If spanwise cracking is detected between the third and tenth
rivet, prior to further flight, reinforce the spar cap in accordance
with paragraph B of the Accomplishment Instructions section of de
Havilland SB No. 6/295, Revision D, dated December 20, 1991, and
repeat the inspection specified in paragraph (a) of this AD inboard
of the reinforced attachment caps at intervals not to exceed 50
hours TIS until a Modification 6/1301 spar cap is installed as
required by paragraph (c) of this AD.
(5) If cracking exceeds a total length of 30 inches but does not
exceed 50 inches, prior to further flight, reinforce the spar cap in
accordance with paragraph B of the Accomplishment Instructions
section of de Havilland SB No. 6/295, Revision D, dated December 20,
1991, and repeat the inspection specified in paragraph (a) of this
AD at intervals not to exceed 600 hours TIS until a Modification 6/
1301 spar cap is installed as required by paragraph (c) of this AD.
(b) Within 100 hours after the effective date of this AD and
thereafter at intervals not to exceed 1,200 hours TIS until a
Modification 6/1301 spar cap is installed as required by paragraph
(c) of this AD, inspect the splice plates of the vertical and
horizontal legs of the rear spar fitting at Wing Stations 87 to 91
for cracks or elongated rivet holes. Prior to further flight,
replace any part that is cracked or has elongated rivet holes with a
serviceable part.
(c) Within 2,400 hours TIS after the effective date of this AD,
replace both wing rear spar caps with a Modification 6/1301 spar cap
in accordance with paragraph C of the Accomplishment Instructions in
de Havilland SB No. 6/295, Revision D, dated December 20, 1991,
unless already accomplished.
(d) Incorporating Modification 6/1301 on both wing rear spar
caps in accordance with paragraph C of the Accomplishment
Instructions in de Havilland SB No. 6/295, Revision D, dated
December 20, 1991, is considered terminating action for the
inspection requirements of this AD.
(e) 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.
(f) 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.
(g) The inspections and modification required by this AD shall
be done in accordance with de Havilland Service Bulletin No. 6/295,
Revision D, dated December 20, 1991. 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.
(h) This amendment (39-9358) supersedes AD 73-05-03, Amendment
39-1658.
(i) This amendment (39-9358) 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. 95-21957 Filed 9-13-95; 8:45 am]
BILLING CODE 4910-13-U
