AD 94-20-07

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AD Number:
94-20-07
Document Type:
AD Final Rules
Docket Number:
93-ANE-12
Subject Heading:
Airworthiness Directives; PTC Aerospace Model 91700 Passenger Oxygen System
Subject:
Passenger Oxygen System
Status:
Current
Citation:
(Federal Register: October 28, 1994 (Volume 59, Number 208))
Citation Publish Date:
10/28/1994
Effective Date:
12/27/1994
Make:
The Boeing Company | PTC Aerospace
Model:
DC-10-10 | DC-10-10F | DC-10-15 | DC-10-30 | DC-10-30F (KC-10A, KDC-10) | DC-10-40 | DC-10-40F | Passenger Oxygen System
Product Type:
Appliance
Product Subtype:
Affected AD:
Superseded AD:
Affected By:
Superseded By:
Service/Office:
Office of Primary Responsibility:
CFR Part Reference:
Part 39 (59 FR 54125 NO. 208 10/28/94)
Comments:
AIRWORTHINESS DIRECTIVES FINAL RULES: 94-20-07
CITATION:   [Federal Register: October 28, 1994 (Volume 59, Number 208)]

PAGE NUMBER:   [Page 54125]

DOCKET NUMBER:   93-ANE-12

AMENDMENT:   39-9035

AD NUMBER:   94-20-07

SUBJECT HEADING:   Airworthiness Directives; PTC Aerospace Model 91700 Passenger Oxygen System

ACTION:   Final rule.

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.

§39.13 - [AMENDED]
2. Section 39.13 is amended by adding the following new airworthiness directive:

REGULATORY TEXT:  
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 sections 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:

Document No.	Pages	Revision	Date
PTC Aerospace SB No. 25-1233	1-18	E	April 15, 1994
Total Pages: 18.			
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.

FOOTER: