Airworthiness Directives; Schweizer Aircraft Corporation and Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, 269C, 269D, and TH- 55A Helicopters

[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

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