[Federal Register Volume 60, Number 211 (Wednesday, November 1, 1995)]
[Rules and Regulations]
[Pages 55443-55445]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-26892]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 92-ASW-01-AD; Amendment 39-9417; AD 95-22-09]


Airworthiness Directives; Boeing Defense and Space Group 
Helicopter Division Model 234 Series Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to Boeing Defense and Space Group Helicopter Division 
(Boeing) Model 234 series helicopters, that currently requires 
inspections of the 

[[Page 55444]]
forward and aft transmission first stage sun and spiral bevel ring gear 
bolted connection (bolted connection). This amendment requires a 
revision to the inspection intervals and criteria used during these 
inspections, as well as adds a visual inspection of the pinion and 
spiral bevel ring gear. This amendment is prompted by reports that 
certain of the affected helicopters have been discovered with loose 
nuts on the bolted connection more frequently than was anticipated in 
the previous AD. The actions specified by this AD are intended to 
prevent wear of the spiral bevel ring gear flange surface, failure of 
the bolted connection, transmission failure, and subsequent loss of 
control of the helicopter.

EFFECTIVE DATE: December 6, 1995.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Defense and Space Group Helicopter Division, P.O. 
16858, Philadelphia, PA 19142-0858. This information may be examined at 
the FAA, Office of the Assistant Chief Counsel, 2601 Meacham Blvd., 
Room 663, Fort Worth, Texas; or at the Office of the Federal Register, 
800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Mr. Raymond Reinhardt, Aerospace 
Engineer, FAA, New York Aircraft Certification Office, Airframe and 
Propulsion Branch, ANE-171, New England Region, 10 Fifth Street, Valley 
Stream, New York 11581, 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) by superseding AD 84-22-04, 
Amendment 39-4943 (49 FR 44093, November 2, 1984), which is applicable 
to Boeing Model 234 series helicopters, was published in the Federal 
Register on August 19, 1992 (57 FR 37481). That action proposed to 
require, within 10 hours time-in-service (TIS) or prior to the 
accumulation of 150 hours TIS for helicopters that conduct six or more 
landings, ground-air-ground cycles, or external load lifts per hour, or 
any combination thereof: (1) An initial Spectrometric Oil Analysis 
Program (SOAP) sample inspection; (2) a visual inspection of the pinion 
and spiral bevel ring gear teeth for scuffing; (3) an initial bolt 
torque inspection of the bolted connection; and (4) thereafter, 
repetitive inspections at 25 hours TIS or 50 hours TIS depending on the 
torque values present on the nuts of the bolted connection when the 
previous inspection was conducted. Additionally, that action proposed 
to require, within 50 hours TIS or prior to the accumulation of 500 
hours TIS for helicopters that conduct less than six landings, ground-
air-ground cycles, or external load lifts per hour or any combination 
thereof: (1) An initial SOAP sample inspection; (2) a visual inspection 
of the pinion and spiral bevel ring gear teeth for scuffing; (3) an 
initial bolt torque inspection of the bolted connection; and (4) 
repetitive inspections at 100 hours TIS or 300 hours TIS depending on 
the torque values present on the nuts of the bolted connection when the 
previous inspection was conducted.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the one comment received.
    The commenter requests an increase in the TIS before the initial 
inspections from 150 to 200 hours TIS, and from 50 to 100 hours TIS 
between the repetitive inspections, and deletion of the proposed 
requirement for a SOAP inspection. The commenter states that with the 
repairs they have made and by using improved lubricants, their 
experience shows that the interval between inspections can be extended. 
The commenter also states that SOAP inspections are already being 
performed; therefore, a SOAP inspection should not be required. The FAA 
neither concurs with increasing the initial nor repetitive inspection 
intervals, nor does it concur in the commenter's position that SOAP 
inspections should not be required. After an analysis of the 
manufacturer's recommendations and the affected helicopter usage, the 
FAA has determined that helicopters involved in operations that require 
constant power changes such as logging, heavy lift operations, or 
several ground-air-ground cycles for each flight hour are more likely 
to be subject to the nut loosening or gear teeth scuffing conditions 
and at a faster rate. Therefore, inspection intervals are spaced such 
that early detection of any unsafe condition or unairworthy part is 
more likely to occur.
    After careful review of the available data, including the comment 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule as proposed, except for 
reorganizing and editorial changes.
    The FAA estimates that 7 helicopters of U.S. registry will be 
affected by this AD, that it will require 100 SOAP and 100 torque 
inspections per year per helicopter, and that it will take 
approximately 2 work hours with a crew of 2 per helicopter to 
accomplish the 50 hour TIS inspection, and 1 work hour with 1 person 
per helicopter to accomplish the SOAP sample inspection. The average 
labor rate is $60 per work hour. Based on these figures, the total cost 
of the AD on U.S. operators is estimated to be $210,000 per 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 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), 40101, 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Amendment 39-4943 (49 FR 
44093, November 2, 1984), and by adding a new airworthiness directive 
(AD), Amendment 39-9417, to read as follows:

AD 95-22-09  Boeing Defense and Space Group Helicopter Division: 
Amendment 39-9417. Docket No. 92-ASW-01-AD. Supersedes AD 84-22-04, 
Amendment 39-4943.


[[Page 55445]]

    Applicability: Model 234 series helicopters, with forward rotor 
transmission, part numbers (P/N) 234D1200-2, -3, or -4, or aft rotor 
transmission, P/N 234D2200-3 or -4, 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 wear of the spiral bevel ring gear flange surface, 
failure of the bolted connection, transmission failure, and 
subsequent loss of control of the helicopter, accomplish the 
following:
    (a) For helicopters that perform six or more landings, ground-
air-ground cycles, or external load lifts per hour, or any 
combination thereof, conduct the following:
    (1) Within the next 10 hours time-in-service (TIS) after the 
effective date of this AD, or prior to the accumulation of 150 hours 
TIS since installed or since the last disassembly of the spiral 
bevel ring gear bolted connection, whichever occurs later, 
accomplish the following:
    (i) Conduct a Spectrometric Oil Analysis Program (SOAP) sample 
inspection in accordance with the applicable maintenance manual.
    (ii) Visually inspect the pinion and spiral bevel ring gear 
teeth for scuffing. If scuffing is found, remove both the pinion and 
the first stage sun and spiral bevel ring gear assemblies, 
disassemble the gear assemblies, inspect them in accordance with the 
applicable overhaul manual, and replace unairworthy parts.
    (iii) Perform a bolt torque inspection of the bolted connection 
in accordance with the applicable maintenance manual.
    (2) Repeat the inspections required by paragraph (a)(1) at 
intervals not to exceed 50 hours TIS if no nuts in the bolted 
connection rotate at a torque below 350 in.-lb.
    (3) Repeat the inspection required by paragraph (a)(1) at 
intervals not to exceed 25 hours TIS if no more than two nuts in the 
bolted connection rotate at a torque below 350 in.-lb., but above 
275 in.-lb.
    (4) Replace the transmission with an airworthy transmission 
prior to further flight if three or more nuts in the bolted 
connection rotate at a torque below 350 in.-lb., or if any nut 
rotates at a torque at or below 275 in.-lb.
    (5) Conduct supplementary SOAP sample inspections at intervals 
not to exceed 25 hours TIS after the last SOAP sample inspection.
    (b) For helicopters that perform less than six landings, ground-
air-ground cycles, or external load lifts per hour, or any 
combination thereof, conduct the following inspections:
    (1) Within the next 50 hours TIS after the effective date of 
this AD, or prior to the accumulation of 500 hours TIS since 
installed or since the last disassembly of the spiral bevel ring 
gear bolted connection, whichever occurs later, accomplish the 
following:
    (i) Conduct a SOAP sample inspection in accordance with the 
applicable maintenance manual.
    (ii) Visually inspect the pinion and spiral bevel ring gear 
teeth for scuffing. If scuffing is found, remove both the pinion and 
and the first stage sun and spiral bevel ring gear assemblies, 
disassemble the gear assemblies, inspect them in accordance with the 
applicable overhaul manual, and replace unairworthy parts.
    (iii) Perform a bolt torque inspection of the bolted connection 
in accordance with the applicable maintenance manual.
    (2) Repeat the inspections required by paragraph (b)(1) at 
intervals not to exceed 300 hours TIS if no nuts in the bolted 
connection rotate at a torque below 350 in.-lb.
    (3) Repeat the inspections required by paragraph (b)(1) at 
intervals not to exceed 100 hours TIS if no more than two nuts in 
the bolted connection rotate at a torque below 350 in.-lb, but above 
275 in.-lb.
    (4) Replace the transmission with an airworthy transmission 
prior to further flight if three or more nuts in the bolted 
connection rotate at a torque below 350 in.-lb., or if any nut 
rotates at a torque at or below 275 in.-lb.
    (5) Conduct supplementary SOAP sample inspections at intervals 
not to exceed 50 hours TIS after the last SOAP sample inspection.

    Note 2: Boeing Helicopters Service Bulletin No. 234-63-1010, 
Revision 4, dated January 31, 1992, pertains to this AD. Boeing 234-
2 Maintenance Manual, section 63-25-50, pertains to this AD. Boeing 
234-5 Overhaul Manual pertains to this AD.

    (c) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used when approved by the Manager, New York Aircraft Certification 
Office. 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 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 December 6, 1995.

    Issued in Fort Worth, Texas, on October 23, 1995.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 95-26892 Filed 10-31-95; 8:45 am]
BILLING CODE 4910-13-U