Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all aircraft equipped with any Puritan-Bennett C351-2000 series passenger oxygen mask or portable oxygen mask having an elastomer cure date between September 1993 and March 1997 was published in the Federal Register as a notice of proposed rulemaking (NPRM) on September 22, 1998 (63 FR 50540). The NPRM proposed to require inspecting the oxygen mask face cushion adjacent to the inner mask housing for any tear, and, if a tear is found, repairing or replacing the passenger or portable oxygen mask with one that has an elastomer cure date later than March 1997.
Accomplishment of the proposed action as specified in the NPRM would be required in accordance with Nellcor Puritan-Bennett Service Bulletin No. C351-2000-35-1, Revision 2, date of original issue: July, 1996; date of first revision: February, 1997; date of current revision: February, 1998.
The NPRM was the result of three airplane manufacturers informing the FAA that the affected oxygen masks were defective.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
Comment Issue No. 1: List in the AD All Passenger Service Units That Could Contain the Affected Oxygen Masks
Two commenters recommend that the FAA provide, in the proposed AD, a listing of the passenger service units (PSU) that could contain the affected oxygen masks. The commenters state that it would be difficult to detect whether one of the affected oxygen masks was in their fleet since passenger or portable oxygen masks are not tracked items. As written, the proposed AD would require inspecting all aircraft and spares in the fleet to determine if the AD applied. The PSU s are equipment that is tracked and including a listing of those would allow the affected operators to check their logbook to determine AD applicability.
The FAA concurs that listing the PSU s in the proposed AD would allow the operators to check the logbook to determine AD applicability. However, the affected passenger and portable oxygen masks can be installed in any PSU. Therefore, if an operator does not track passenger and portable oxygen masks, the FAA knows of no other way to assure that the unsafe condition does not go undetected than to inspect each PSU to determine if the affected masks are installed.
No changes to the final rule are required as a result of these comments.
Comment Issue No. 2: Cost Impact of the Proposed AD
Two commenters feel that the FAA s determination of the cost impact on U.S. operators of the airplanes that have the affected passenger or portable oxygen masks installed is misleading. In particular, these comments are as follows:
One commenter states that the cost to inspect each of his/herfleet s aircraft to determine if the affected oxygen masks are installed on each PSU is 6 workhours per aircraft; and
The other commenter states that the FAA intended to use the cost calculation of 1 workhour per aircraft for labor time, but instead multiplied that by the number of masks affected.
The FAA concurs that the cost impact of the proposed AD is misleading. The FAA has no way of determining the exact number of affected portable and passenger oxygen masks that would need to be either inspected and, if necessary, repaired or replaced on each airplane. For this reason, the FAA is writing the Cost Impact section in the final rule to account for the cost per mask and not per airplane.
Comment Issue No. 3: Make the Inspection Repetitive
One commenter recommends that the FAA make the proposed inspections repetitive. This commenter makes this recommendation based on the belief that the unsafe condition is a result of aging and fatigue damage to the affected portable and passenger oxygen masks.
The FAA does not concur that the inspection should be made repetitive. The oxygen masks that are unsafe were torn at the factory due to a manufacturing defect. This FAA has determined the time range of when these torn oxygen masks were manufactured. The proposed AD would require repair or replacement of any oxygen mask manufactured during a certain time and revealing a tear, and would prohibit future installation of any oxygen mask that has a tear.
Therefore, no changes to the final rule are required as a result of these comments.
Comment Issue No. 4: Extend the Compliance Time
One commenter recommends that the FAA extend the compliance time of the proposed AD. This commenter states that the 90 calendar day compliance time would be difficult to meet and the economic impact due to unnecessary downtime would be significant. The commenter suggests a 6 calendar month compliance time to coincide with regularly scheduled maintenance.The FAA concurs. The FAA initially chose 90 calendar days based upon a balance between safety and practicality of implementation. The commenter presents a strong case for extending the compliance time based upon practicality of implementation and the FAA has determined that extending to 6 calendar months will not adversely affect aviation safety.
The compliance time of the final rule has been changed accordingly.
The FAA's Determination
After careful review of all available information related to the subject presented above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for the change in the write-up in the Cost Impact section, the change in compliance time, and minor editorial corrections. The FAA has determined that these changes and the minor editorial corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.
Cost ImpactThe FAA estimates that 10,500 oxygen masks will be affected by this AD, that it will take approximately 1 workhour per oxygen mask to accomplish the inspection and replacement, and that the average labor rate is approximately $60 an hour. Puritan-Bennett will repair or replace oxygen mask assemblies found defective at no cost to the owner/operator of any affected aircraft. Based on these figures, the total cost impact of the inspection is estimated to be $630,000, or $60 per mask. The cost per aircraft will vary based on the number of oxygen masks each aircraft has installed and the number that would require replacement.
Compliance Time
The compliance time of this AD is presented in calendar time instead of hours time-in-service (TIS). The FAA has determined that calendar time compliance is the most desirable method because the use of these oxygen masks is not related to hours time-in-service. The unsafe condition exists regardless of whether the aircraft is in operation. Therefore, to assure that the above-referenced condition is corrected within a reasonable period of time, a compliance schedule based upon calendar time instead of hours TIS is utilized.
Regulatory Impact
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 numberof small entities under the criteria of the Regulatory Flexibility Act. A copy of the final evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting 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. 106(g), 40113, 44701.
39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: