AD Amdt-39-11002

[Federal Register Volume 64, Number 11 (Tuesday, January 19, 1999)]
[Rules and Regulations]
[Pages 2821-2823]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 99-1064]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-SW-13-AD; Amendment 39-11002; AD 98-26-06]


Airworthiness Directives; Schweizer Aircraft Corporation Model 
269D Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

-----------------------------------------------------------------------

SUMMARY: This document publishes in the Federal Register an amendment 
adopting Airworthiness Directive (AD) 98-26-06 which was sent 
previously to all known U.S. owners and operators of Schweizer Aircraft 
Corporation (Schweizer) Model 269D helicopters by individual letters. 
This AD requires removing the main rotor drive shaft (shaft) and 
inspecting it for cracks. If a crack is found, replacing the shaft with 
an airworthy shaft is required. This AD also requires periodically 
verifying the torque of the main rotor hub (hub) bolts. This amendment 
is prompted by four reports of cracking in the shaft of helicopters 
with a large diameter hub. Wear patterns indicate cracking was caused 
by loss of clamping torque on the hub and shaft assembly due to the use 
of grease between the hub and shaft. This condition, if not corrected, 
could result in failure of the shaft and subsequent loss of control of 
the helicopter.

DATES: Effective February 3, 1999, to all persons except those persons 
to whom it was made immediately effective by Priority Letter AD 98-26-
06, issued on December 9, 1998, which contained the requirements of 
this amendment.
    Comments for inclusion in the Rules Docket must be received on or 
before March 22, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 98-SW-13-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Raymond H. Reinhardt, Aerospace 
Engineer, Airframe and Propulsion Branch, ANE-171, FAA, New York 
Aircraft Certification Office, 10 Fifth St., Valley Stream, NY, 
telephone (516) 256-7532, fax (516) 568-2716.

SUPPLEMENTARY INFORMATION: On December 9, 1998, the FAA issued Priority 
Letter AD 98-26-06, applicable to Schweizer Model 269D helicopters, 
which requires removing the shaft and inspecting it for cracks. If a 
crack is found, replacing the shaft with an airworthy shaft is 
required. That AD also requires periodically verifying the torque of 
the hub bolts. That action was prompted by four reports of cracking in 
the shaft of helicopters with a large diameter hub. Wear patterns 
indicate cracking was caused by loss of clamping torque on the hub and 
shaft assembly due to the use of grease between the hub and shaft. A 
pilot reported excessive vibration in one incident. An inspection 
following that incident revealed a 2.5-inch horizontal crack in the 
shaft. The crack started from one of the three lower bolt holes, 
propagated to an adjacent bolt hole, and then propagated from the 
second bolt hole in a downward direction. This condition, if not 
corrected, could result in failure of the shaft and subsequent loss of 
control of the helicopter.
    Since the unsafe condition described is likely to exist or develop 
on other Schweizer Model 269D helicopters of the same type design, the 
FAA issued Priority Letter AD 98-26-06 to prevent failure of the shaft 
and subsequent loss of control of the helicopter. The AD requires, 
prior to 200 hours time-in-service (TIS), and thereafter at intervals 
not to exceed 100 hours TIS, inspecting the shaft for cracks in the 
area of the six hub attach bolts using a 10-power or higher magnifying 
glass and bright light. If no crack is found as a result of the visual 
inspection, the AD requires inspecting the shaft using a magnetic 
particle inspection method. If a crack is found, the AD requires 
replacing the shaft with an airworthy shaft. The AD also requires 
periodically verifying the torque of the hub bolts. The short 
compliance time involved is required because the previously described 
critical unsafe condition can adversely affect the controllability of 
the helicopter. Therefore, the inspections and replacement, if 
necessary, are required prior to further flight, and this AD must be 
issued immediately.
    Since it was found that immediate corrective action was required, 
notice and opportunity for prior public comment thereon were 
impracticable and contrary to the public interest, and good cause 
existed to make the AD effective immediately by individual letters 
issued on December 9, 1998, to all known U.S. owners and operators of 
Schweizer Model 269D helicopters. These conditions still exist, and the 
AD is hereby published in the Federal Register as an amendment to 
section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to 
make it effective to all persons.
    The FAA estimates that 6 helicopters of U.S. registry will be 
affected by this AD, that it will take approximately 2 work hours for 
the periodic inspections and 22 work hours to replace the shaft, if 
necessary, per helicopter, and the average labor rate is $60 per work 
hour. Required parts will cost approximately $12,000 per replacement 
shaft. Based on these figures, the total cost impact of the AD on U.S. 
operators is estimated to be $80,640 to replace the shafts in all the 
helicopters, and $7,200 a year for 10 inspections per year on each 
helicopter.

[[Page 2822]]

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications should identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. 98-SW-13-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

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:

98-26-06  Schweizer Aircraft Corporation: Amendment 39-11002. Docket 
No. 98-SW-13-AD.

    Applicability: Model 269D helicopters with a large diameter main 
rotor hub (hub), part number (P/N) 269A1002-11, and main rotor drive 
shaft (shaft), P/N 269A5305-139, -143, -145, or -147, 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 (c) 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 
remove any helicopter from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the shaft and subsequent loss of control 
of the helicopter, accomplish the following:
    (a) Prior to 200 hours time-in-service (TIS) since the assembly 
of the hub and a shaft having zero hours TIS, and thereafter at 
intervals not to exceed 100 hours TIS,
    (1) Remove the shaft from the power train system.
    (2) Clean and inspect the shaft for a crack in the area of the 
six hub attach bolt (bolt) holes using a 10-power or higher 
magnifying glass and bright light.
    (3) If no crack is found, inspect the shaft using a direct or 
indirect magnetic particle inspection method in accordance with ASTM 
Standard No. E1444 as follows:
    (i) For direct magnetization, use an AC, DC, or AC/DC wet 
continuous method with fluorescent or nonfluorescent particles.
    (A) Circular (Head Shot)--1,100 amperes
    Look for a longitudinal crack.
    (B) Longitudinal (Coil Shot)--Because of variations in coil 
design, only the length-to-diameter ratio based on effective 
diameter and inspection region is provided.
    Effective diameter--1.279 inches,
    Length--6.00 inches,
    L/D Ratio--5,
    Look for a circumferential crack.
    (C) Demagnetize and clean the inspection areas with solvent to 
remove residual particles.
    (ii) For indirect magnetization, use an AC electromagnetic yoke 
(Magnaflux product No. Y-6 or equivalent). Set the spacing and the 
angle to suit the external diameter of the shaft.
    (A) Magnetize each of the six hole areas by applying the AC 
electromagnetic yoke (yoke) circumferentially across the hole.
    (B) During each magnetization, apply dry color contrasting 
particles to the inspection area and look for a circumferential 
crack propagating from any hole.
    (C) Demagnetize and repeat the inspections with the poles of the 
yoke positioned longitudinally across each hole group looking for a 
circumferential crack.
    (D) Demagnetize and clean the inspection areas with solvent to 
remove residual particles.
    (iii) If no crack is found as a result of the magnetic particle 
inspection, reassemble the hub and shaft.

    Note 2: Procedures in Model 269D Handbook of Maintenance 
Instructions (HMI) revised on June 12, 1998, include installing a 
three-piece retention fitting, applying a higher torque to each 
bolt, assembling with no lubricant, and applying zinc chromate 
primer between the hub and the shaft.

    (4) If a crack is found, replace the shaft with an airworthy 
shaft.
    (b) At intervals not to exceed 50 hours TIS after accomplishing 
paragraph (a),
    (1) Unsafety and clean the exterior of the bolts.
    (2) Unsafety and loosen the droop stop nut.
    (3) Apply 390 in-lbs of torque to each of the six bolts. If any 
bolt rotates, accomplish the requirements of paragraph (a).
    (4) Apply 390 to 410 in-lbs of torque to each of the six bolts 
and resafety.
    (5) Torque and safety the droop stop nut.
    (6) Seal the exterior of the bolts and washers with a corrosion 
preventative compound.
    (c) 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

[[Page 2823]]

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 3: 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.

    (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 helicopter to a location where 
the requirements of this AD can be accomplished.
    (e) This amendment becomes effective on February 3, 1999, to all 
persons except those persons to whom it was made immediately 
effective by Priority Letter AD 98-26-06, issued December 9, 1998, 
which contained the requirements of this amendment.

    Issued in Fort Worth, Texas, on January 8, 1999.
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 99-1064 Filed 1-15-99; 8:45 am]
BILLING CODE 4910-13-P