[Federal Register Volume 59, Number 208 (Friday, October 28, 1994)]
[Unknown Section]
[Page ]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-26139]


[Federal Register: October 28, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-ANE-12; Amendment 39-9035; AD 94-20-07]


Airworthiness Directives; PTC Aerospace Model 91700 Passenger 
Oxygen System

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to PTC Aerospace Model 91700 passenger oxygen system, 
installed in PTC Aerospace Model 881, 940, and 950 seats installed on 
McDonnell Douglas DC-10 series aircraft. This AD requires a one-time 
inspection to verify the proper configuration and functioning of the 
passenger oxygen system, and replacement, if necessary, with 
serviceable parts. This amendment is prompted by oxygen canisters 
failing to activate due to the installation of incorrect pin release 
brackets or defective oxygen canister release pins. The actions 
specified by this AD are intended to prevent failure of the passenger 
oxygen system to activate.

DATES: Effective December 27, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of December 27, 1994.

ADDRESSES: The service information referenced in this AD may be 
obtained from PTC Aerospace, 607 Bantam Road, Litchfield, CT 06759. 
This information may be examined at the Federal Aviation Administration 
(FAA), New England Region, Office of the Assistant Chief Counsel, 12 
New England Executive Park, Burlington, MA; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, Washington, 
DC.

FOR FURTHER INFORMATION CONTACT: Terry Fahr, Aerospace Engineer, Boston 
Aircraft Certification Office, FAA, Engine and Propeller Directorate, 
12 New England Executive Park, Burlington, MA 01803-5299; telephone 
(617) 238-7155, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to PTC Aerospace Model 91700 
passenger oxygen system, installed in PTC Aerospace Model 881, 940, and 
950 seats found on McDonnell Douglas DC-10 series aircraft, was 
published in the Federal Register on September 21, 1993 (58 FR 48486). 
That action proposed to require a one-time inspection to verify the 
proper configuration and functioning of the passenger oxygen system, 
and replacement, if necessary, with serviceable parts. The actions 
would be required to be accomplished in accordance with PTC Service 
Bulletin (SB) No. 25-1233, Revision D, dated February 2, 1993, that 
describes procedures for a one-time inspection to verify the proper 
configuration and functioning of the passenger oxygen system, and 
replacement, if necessary, with serviceable parts.
    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 supports the rule as proposed.
    Two commenters state that the compliance time should be reduced, 
one to six months after the effective date of the AD, the other to 30 
days. The Federal Aviation Administration (FAA) does not concur. 
Neither comment offered engineering or technical data to support a 
reduction in the compliance interval from the 15-month compliance time 
contained in the proposed rule. The proposed compliance time was 
determined to provide an acceptable level of safety considering the 
maintenance schedules of the operators. Therefore, the FAA has retained 
the 15-month compliance time in the final rule.
    One commenter states that the lanyard length check should be 
deleted due to difficulty in performing that check. The FAA concurs 
that the check was difficult to perform but does not concur in deleting 
the check. The check is needed to verify the correct lanyard length. 
Since publication of the NPRM, the manufacturer has advised the FAA 
that the lanyard length tolerance has been increased to plus or minus 
.25 inch, which will allow that check to be more easily accomplished. 
This tolerance factor has been added to paragraph (a)(3) of this Final 
rule.
    One commenter states that the AD should require repetitive 
inspections. The FAA does not concur. The one-time inspection, and 
replacement, if necessary, with serviceable parts, required by this AD 
will obviate the need for repetitive inspections other than those 
performed during routine scheduled maintenance.
    The commenter further states that the AD should contain a 
requirement for reporting malfunctions. The FAA does not concur. The 
one-time inspection, and replacement, if necessary, with serviceable 
parts, required by this AD will preclude the need for reporting 
malfunctions.
    The commenter further states that the SB does not provide adequate 
work step instructions. The FAA concurs. Since issuance of the NPRM, 
PTC Aerospace has issued SB No. 25-1233, Revision E, dated April 15, 
1994, which contains clarified work step instructions. The FAA has 
added this new service bulletin to the AD.
    The commenter further states that the SB should specify a different 
oxygen canister safety cap. The revised SB specifies two safety caps.
    The commenter further states that a functional test should be 
required prior to disassembly. The FAA does not concur. The FAA has 
determined that a functional test prior to disassembly would not 
provide any benefit in evaluating the passenger oxygen system.
    The commenter further states that there should be a snag test on 
the release pin for grooves and burrs. The FAA does not concur. The FAA 
believes that the instructions for testing as stated in the revised SB 
are adequate.
    Since publication of the NPRM, the manufacturer has advised the FAA 
that an additional safety cap, Scott Part Number (P/N) 36425-00, is 
available. Also, the manufacturer has added a black plastic grommet, P/
N 91880-2, on the pin release bracket, and a bushing, P/N 121836-1, on 
the activator assembly spring, P/N H13341. Finally, the manufacturer 
has included instructions for verifying the gap between the cable 
actuating lever and the cable activating lever stop in PTC Aerospace SB 
No. 25-1233, Revision E, dated April 15, 1994. These revised 
instructions have been added to the compliance section of this final 
rule.
    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 changes described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    The initial estimate in the NPRM of approximately 3,000 passenger 
oxygen systems of the affected design in the worldwide fleet was 
incorrect. The manufacturer has advised the FAA that the revised number 
is 4,800 passenger oxygen systems in the worldwide fleet. The FAA 
estimates that 4,000 passenger oxygen systems are installed on aircraft 
of U.S. registry, of which 2,500 have already been modified, leaving 
approximately 1,500 passenger oxygen systems that have not yet been 
modified in accordance with this AD. The FAA estimates that it will 
take approximately 1 work hour per passenger oxygen system to 
accomplish the required actions, and that the average labor rate is $55 
per work hour. Required parts will cost approximately $20 per passenger 
oxygen system. Based on these figures, the total cost impact of the AD 
on U.S. operators is estimated to be $112,500.
    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, 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13   [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

94-20-07  PTC Aerospace: Amendment 39-9035. Docket 93-ANE-12.

    Applicability: PTC Aerospace Model 91700 passenger oxygen 
system, installed in PTC Aerospace Model 881, 940, and 950 seats, 
installed on McDonnell Douglas DC-10 series aircraft.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the passenger oxygen system to activate, 
accomplish the following:
    (a) Within 15 months after the effective date of this AD, or the 
next seat removal, whichever occurs first, verify the proper 
configuration and functioning of the passenger oxygen system in 
accordance with PTC Aerospace Service Bulletin No. 25-1233, Revision 
E, dated April 15, 1994, as follows:
    (1) Remove the seat bottom cushion and open the oxygen housing 
assembly door, Part Number (P/N) 91626, to expose the oxygen 
canister and lower firing system. On the Model 950 seats, remove 
fastening screws of the center console, P/N 98154, and rotate the 
console forward in addition to removing the cushion.
    (2) Install an oxygen canister safety cap, Tri-Star P/N CD3, or 
Scott P/N 36425, to prevent discharging of the oxygen canister.
    (3) Remove the cable release assembly, P/N 91601. Verify that 
the assembly is the correct length (10.25 inches plus or minus .25 
inch), that the release pin, P/N 91587-1, is free of burrs and 
notches, and that the nylon cord is not worn and is free of any burn 
damage. If any discrepancies are found, replace with a serviceable 
unit.
    (4) Verify installation of the correct pin release bracket, P/N 
91602-1. A correct bracket has its plastic grommet located 
vertically above the oxygen canister release sleeve. If the bracket 
is found to be misaligned, replace it with a correct bracket. 
Replace the white plastic grommet with a new black plastic grommet, 
P/N 122326, securing it with Devo 44044 cyanoacrylate adhesive or 
equivalent. The grommet is correctly positioned when the grommet 
slot is aligned with the pin release bracket slot.
    (5) Reassemble the cable release assembly with the safety cap on 
the oxygen canister. Adjust and tighten the jam nuts, P/N H12292, to 
obtain a gap between the cable actuating lever, P/N 91599-1 or -2, 
and cable actuating lever stop, P/N 87310-3, within .03 inch and .25 
inch. Verify that the nylon cord will not contact the oxygen 
canister in the assembled configuration and that the cable release 
pin will release from the oxygen canister with a tension of one 
pound or less. If any discrepancies are found, replace the cable 
release assembly with a serviceable unit.
    (6) Remove the oxygen masks from the seat back housing. Compress 
the actuator assembly spring, P/N H13341, and install a bushing, P/N 
121836-1, oriented so that the spring seats in the bushing's 
counterbore.
    (7) Reassemble the oxygen system components with the safety cap 
on the oxygen canister. Verify that the oxygen system functions 
properly by verifying that the lanyard assembly release pin, P/N 
91587-1, releases from the oxygen canister when the masks are pulled 
from the seat back housing. If any discrepancies are found, replace 
the oxygen system with a serviceable unit.
    (b) 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, Boston Aircraft Certification 
Office. The request should be forwarded through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Boston Aircraft Certification Office.

    Note: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Boston Aircraft Certification 
Office.

    (c) Special flight permits may be issued in accordance with 
Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 
21.197 and 21.199) to operate the aircraft to a location where the 
requirements of this AD can be accomplished.
    (d) The verification and modification shall be done in 
accordance with the following service bulletin: 

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       Document No.           Pages     Revision            Date        
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PTC Aerospace..............                                             
SB No. 25-1233.............     1-18  E             April 15, 1994.     
                            -----------------------                     
    Total:.................     18.                                     
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    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 PTC Aerospace, 607 Bantam Road, Litchfield, 
CT 06759. Copies may be inspected at the FAA, New England Region, 
Office of the Assistant Chief Counsel, 12 New England Executive Park, 
Burlington, MA; or at the Office of the Federal Register, 800 North 
Capitol Street NW., suite 700, Washington, DC.
    (e) This amendment becomes effective on December 27, 1994.

    Issued in Burlington, Massachusetts, on September 12, 1994.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.

[FR Doc. 94-26139 Filed 10-27-94; 8:45 am]

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