[Federal Register Volume 63, Number 170 (Wednesday, September 2, 1998)]
[Rules and Regulations]
[Pages 46645-46647]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-23600]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-SW-10-AD; Amendment 39-10727; AD 98-18-11]
RIN 2120-AA64
Airworthiness Directives; Schweizer Aircraft Corporation and
Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, 269C, 269D, and TH-
55A Helicopters
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to Schweizer Aircraft Corporation and Hughes Helicopters,
Inc. Model 269A, 269A-1, 269B, 269C, 269D, and TH-55A helicopters, that
requires a visual inspection of the bond line between the main rotor
blade abrasion strip (abrasion strip) and the blade for voids,
separation, or lifting of the abrasion strip; a visual inspection of
the adhesive bead around the perimeter of the abrasion strip for
erosion, cracks, or blisters; a tap (ring) test of the abrasion strip
for evidence of debonding or hidden corrosion voids; and removal of any
blade with an unairworthy abrasion strip and replacement with an
airworthy blade. This amendment is prompted by four reports that
indicate that debonding and corrosion have occurred on certain blades
where the abrasion strip attaches to the blade skin. The actions
specified by this AD are intended to prevent loss of the abrasion strip
from the blade and subsequent loss of control of the helicopter.
EFFECTIVE DATE: October 7, 1998.
FOR FURTHER INFORMATION CONTACT: Mr. Raymond Reinhardt, Aerospace
Engineer, FAA, New York Aircraft Certification Office, Airframe and
Propulsion Branch, Engine and Propeller Directorate, 10 Fifth Street,
3rd Floor, Valley Stream, New York 11581-1200, telephone (516) 256-
7532, fax (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 is
applicable to Schweizer Aircraft Corporation and Hughes Helicopters,
Inc. Model 269A, 269A-1, 269B, 269C, 269D, and TH-55A series
helicopters was published in the Federal Register on October 30, 1996
(61 FR 55937). That action proposed to require, for each blade, a
visual inspection of the bond line between the abrasion strip and the
blade for voids, separation, or lifting of the abrasion strip; a visual
inspection of the adhesive bead around the perimeter of the abrasion
strip for erosion, cracks, or blisters; a tap (ring) test of the
abrasion strip for evidence of debonding or hidden corrosion voids; and
removal of any blade with a defective abrasion strip and replacement
with an airworthy blade. If any deterioration of the abrasion strip
adhesive bead was discovered, restoration of the bead in accordance
with the applicable maintenance manual was proposed. If an abrasion
strip void was found or suspected, removing and replacing the blade
with an airworthy blade was also proposed.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
One commenter states that Model 269C-1 helicopters should be
included in the Applicability section of the AD, because this model,
which was recently type certificated, could be retro-fitted with any of
the affected blades listed in the proposed AD. The FAA concurs,
[[Page 46646]]
and future rulemaking action will address this issue.
The same commenter states that a terminating action should be added
to the AD. The commenter states that if any of the affected blades are
subject to an abrasion strip repair, those blades should no longer be
subject to the repetitive inspections listed in the AD. The FAA
concurs, and a paragraph will be added to the AD to state that, for an
affected blade, blade abrasion strip repair is considered a terminating
action for the requirements of this AD. A requirement was added to
identify repaired blades.
Another commenter states that the abrasion strip inspections called
out in the proposed AD are inadequate to detect defective abrasion
strips. The FAA does not concur; the specified inspections are adequate
to detect defective abrasion strips and these inspections will remain
in the AD.
The commenter also states that current abrasion strip materials and
abrasion strip bonding methods are inadequate to assure long-term
durability. The FAA does not concur; when performed correctly the
current abrasion strip materials and abrasion strip bonding methods are
adequate and demonstrate an acceptable service life.
Finally, the commenter would like the FAA to re-evaluate current
regulations pertaining to abrasion strip technology and revise the
regulations to include minimum performance criteria for adhesively
bonded abrasion strip assemblies. The FAA does not concur; current
regulations have demonstrated an acceptable level of safety for
abrasion strip bonding.
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the change described
previously, as well as with other non-substantive changes. The FAA has
determined that these changes will neither increase the economic burden
on any operator nor increase the scope of the AD.
The FAA estimates that 100 helicopters of U.S. registry will be
affected by this AD, that it will take approximately one-third of a
work hour per helicopter to conduct the initial inspections;
approximately one-third of a work hour to conduct the repetitive
inspections; approximately 11 work hours to remove and reinstall a
blade; and approximately 32 work hours to repair the blade; and that
the average labor rate is $60 per work hour. Required parts
(replacement abrasion strips) will cost approximately $57 per main
rotor abrasion strip (each helicopter has three main rotor blades).
Based on these figures, the total cost impact of the AD on U.S.
operators is estimated to be $135,850 per year for the first year and
$133,850 for each year thereafter, assuming one-sixth of the affected
blades in the fleet are removed, repaired, and reinstalled each year,
and that all affected helicopters are subjected to one repetitive
inspection each year.
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 final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it may be obtained
from the Rules Docket at the FAA, Office of the Regional Counsel,
Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas
76137.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, 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), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive
to read as follows:
AD 98-18-11 Schweizer Aircraft Corporation and Hughes Helicopters,
INC.: Amendment 39-10727. Docket No. 96-SW-10-AD.
Applicability: Model 269A, 269A-1, 269B, and TH-55A helicopters
with main rotor blades, part number (P/N) 269A1190-1, serial numbers
(S/N) S0001 through S0012 installed; and Model 269C and 269D
helicopters with main rotor blades, P/N 269A1185-1, S/N S222, S312,
S313, S325 through S327, S339, S341, S343, S346, S347, S349 through
S367, S369 through S377, S379 through S391, S393 through S395, S397,
S399, S401 through S417, S419 through S424, S426 through S449, S451
through S507, S509 through S513, S516 through S527, S529 through
S540, S542, S544 through S560, S562 through S584, S586 through S595,
S597 though S611, S620 through S623, S625, S628, S633, S641 through
S644, S646, S653, S658, S664, S665, and S667, installed,
certificated in any category.
Note 1: This AD applies to each helicopter 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 helicopters that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must use the authority
provided in paragraph (e) to request approval from the FAA. This
approval may address either no action, if the current configuration
eliminates the unsafe condition, or different actions necessary to
address the unsafe condition described in this AD. Such a request
should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
(except for the repair of the abrasion strip) remove any helicopter
from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent loss of the abrasion strip from a main rotor blade
(blade) and subsequent loss of control of the helicopter, accomplish
the following:
(a) Within the next 50 hours time-in-service (TIS), or within 90
calendar days after the effective date of this AD, whichever is
earlier, or prior to installing an affected replacement blade, and
thereafter at intervals not to exceed 50 hours TIS from the date of
the last inspection or replacement installation:
(1) Visually inspect the adhesive bead around the perimeter of
each abrasion strip for erosion, cracks, or blisters.
(2) Visually inspect the bond line between each abrasion strip
and each blade skin for voids, separation, or lifting of the
abrasion strip.
(3) Inspect each abrasion strip for debonding or hidden
corrosion voids using a tap (ring) test as described in the
applicable maintenance manual.
[[Page 46647]]
(b) If any deterioration of an abrasion strip adhesive bead is
discovered, prior to further flight, restore the bead in accordance
with the applicable maintenance manual.
(c) If abrasion strip debonding, separation, or a hidden
corrosion void is found or suspected, prior to further flight,
remove the blade with the defective abrasion strip and replace it
with an airworthy blade.
(d) Repair of an affected blade's abrasion strip is considered a
terminating action for the requirements of this AD. Identify the
repaired blade with a white dot added adjacent to the blade S/N.
(e) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, New York Aircraft Certification
Office, FAA. Operators shall submit their requests through an FAA
Principal Maintenance Inspector, who may concur or comment and then
send it to the Manager, New York Aircraft Certification Office.
Note 2: 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.
(f) 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 helicopter to a location where
the requirements of this AD can be accomplished, provided the
abrasion strip has not started to separate or debond from the main
rotor blade.
(g) This amendment becomes effective on October 7, 1998.
Issued in Fort Worth, Texas, on August 21, 1998.
Larry M. Kelly,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 98-23600 Filed 9-1-98; 8:45 am]
BILLING CODE 4910-13-U
