Discussion
What caused this AD? Several operators of Raytheon Beech Models 1900C and 1900D airplanes have reported chafing of the wing fuel quantity wiring harness against the wing fuel quantity wiring harness supports (located at the wing wiring harness lighting hole mounts). The Model 1900C (C- 12J) airplanes are also susceptible to this condition.
The lightning hole mounts at each wing rib support the wing fuel quantity wiring harness. The following could occur and cause the above-referenced condition:
- Vibration and fuel movement cause the insulation on the wiring harness to chafe on the tie straps used to secure the harness to the lightning hole mounts; and
- Exposed conductors of the wiring harness could then contact each other and result in an incorrect fuel quantity indication or the indicator reading zero.
In addition to the above condition on the Raytheon Beech Models 1900C, 1900C (C-12J), and 1900D airplanes, the O-ringsin Wiggins couplings that join the electrical conduit internal to the wing fuel tanks could leak and allow fuel to enter the conduit. This could result in a fire or explosion.
What is the potential impact if FAA took no action? If not corrected in a timely manner, the above-referenced conditions could result in the following:
- Chafing between the wing fuel quantity wiring harness and the internal wing harness supports at each wing rib location could cause the fuel quantity indication to become unreliable. This could leave the flight crew without an indication of the amount of fuel in the airplane during flight; and
- Fuel leaking through the wiring carry-through conduit and into the wing tip or wheel well area could lead to a fire or explosion.
Has FAA taken any action to this point? We issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain Raytheon Beech Models 1900C, 1900C (C-12J), and 1900D airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on March 22, 2000 (65 FR 15278). The NPRM proposed to require you to install a spiral wrap around the wing fuel quantity wiring harness and apply an adhesive sealant to the Wiggins couplings on the internal fuel tank wiring carry-through conduit. Accomplishment of the proposed action as specified in the NPRM would be in accordance with Raytheon Mandatory Service Bulletin No. SB 28-3299, Issued: December, 1999.
Was the public invited to comment? The FAA encouraged interested persons to participate in the making of this amendment. The following presents the comments received on the proposal and FAA's response to each comment:
Comment Issue No. 1: Provide Information on Allowable Fuel Quantity Wire Harness Chafing What is the commenter's concern? One commenter states that the NPRM does not clarify how much chafing damage is allowed before the fuel quantity harnessmust be replaced. The commenter requests that FAA include allowable limits, sketches, or definitions that dictate how much chafing is allowed on the fuel quantity harness.
What is FAA's response to the concern? The intent of this AD action is to provide protection for the fuel quantity harness so that chafed or shorted wing fuel quantity harness wires do not occur on the affected airplanes. We believe that incorporating the actions of the proposed AD will provide the protection necessary on the fuel quantity harness. This NPRM does not propose replacement or repair of the fuel quantity harness. As with any aircraft part, the fuel quantity harness should be replaced if it has deteriorated to a point where it is not effective.
We are not changing the AD as a result of this comment.
Comment Issue No. 2: FAA's Labor Cost Estimate Does Not Reflect the Work
What is the commenters' concern? Two commenters do not believe that FAA's estimate of the number of workhours necessary to accomplish the actions proposed in the NPRM is correct. One commenter states that, based on discussions with other operators, the workhours should be increased from 10 to 12. Another commenter believes 20 workhours is appropriate and lists all the steps necessary to accomplish the proposed actions.
What is FAA's response to the concern? The procedures necessary to accomplish the actions proposed in the NPRM are included in Raytheon Mandatory Service Bulletin No. SB 28-3299, Issued: December, 1999. We obtained the 10-workhour figure directly from this service bulletin. Raytheon has informed us that several owners/operators of the affected airplanes have already had the proposed actions accomplished and that on average the 10-hour estimate is correct. Some airplanes may require more time and some may require less. The exact time is dependent upon the experience of the mechanic, the availability of proper equipment, and the condition of the wire harness as stated in the "Manpower" section of the service bulletin.
We are not changing the AD as a result of these comments.
Comment Issue No. 3: Cost Impact Does not Include Harness Replacement and Aircraft Down Time
What is the commenter's concern? One commenter states that FAA failed to include the cost of replacing damaged fuel quantity harnesses and the revenues lost by taking the airplanes out of operation to accomplish the AD action. What is FAA's response to the concern? As we stated earlier, the intent of this AD action is to provide protection for the fuel quantity harness so that chafed or shorted wing fuel quantity harness wires do not occur on the affected airplanes. The cost impact of this AD addresses the cost of the actions to meet this intent. The FAA has no way of determining the number of fuel quantity harnesses that may need to be replaced. We also cannot estimate the revenue certain operators may lose while accomplishing the AD action. We did however structure the compliance time of the proposed AD to coincide with regularly scheduled maintenance activities.
We are not changing the AD as a result of this comment.
Comment Issue No. 4: Compliance Time is too Short
What is the commenter's concern? One commenter states that the compliance time of 3 months or 600 hours time-in-service (TIS), whichever occurs first, will require some operators to accomplish the AD action within 9 to 10 weeks. We infer that the commenter wants the compliance time extended.
What is FAA's response to the concern? The FAA established the compliance time so that the accomplishment of the AD could coincide with regularly scheduled maintenance activities. Raytheon has informed us that many aircraft are already in compliance with the AD. For these reasons, we believe that the compliance time gives all airplane owners/operators ample time to complete the AD action. As with any AD action, we will consider compliance time extensions provided they provide an acceptable level of safety and are submitted through the alternative method of compliance procedures specified in the AD.
We are not changing the AD as a result of this comment.
Comment Issue No. 5: AD is not Justified
What is the commenter's concern? One commenter states that its maintenance database does not contain information to support the actions proposed in the NPRM. This commenter also believes that placing sealer over the Wiggins fitting does not guarantee that the fitting will not leak. We infer that the commenter wants FAA to withdraw the NPRM.
What is FAA's response to the concern? Raytheon provided FAA with several reports of chafed and shorted fuel quantity harness wires that were found during maintenance and refurbishment. Although the addition of sealer to the fitting cannot provide a guarantee that it will never leak (nothing will provide this guarantee), we have determined that the likelihood of leakage is greatly reduced.
We are not changing the AD as a result of this comment.
The FAA's Determination
What is FAA's final determination on this issue? We carefully reviewed all available information related to the subject presented above and determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. We determined that these minor corrections:
- will not change the meaning of the AD; and
- will not add any additional burden upon the public than was already proposed.
Compliance Time of This AD
What is the compliance time of this AD? The compliance time of this AD is whichever of the following that occurs first:
- within the next 3 months after the effective date of this AD; or
- within the next 600 hours TIS after the effective date of this AD.
Why is the compliance time in both calendar time and hours TIS? Chafing damage is a direct result of airplane usage; however, the fuel leakage problem could result regardless of whether the airplane is utilized. Therefore, to assure that both problems are addressed in a timely manner without inadvertently grounding any of the affected airplanes, we are utilizing a compliance based upon both hours TIS and calendar time.
Cost Impact
How many airplanes does this AD impact? The FAA estimates that 303 airplanes in the U.S. registry will be affected by this AD.
What is the cost impact for the affected airplanes on the U.S. Register? We estimate that it will take approximately 10 workhours per airplane to accomplish the actions required by this AD, and that the average labor rate is approximately $60 an hour. There is no cost for parts to accomplish this AD. Based on these figures, we estimate the total cost impact of this AD on U.S. operators at $181,800, or $600 per airplane.
Regulatory Impact
Does this AD impact various entities? The regulations adopted herein will not have a substantial direct effect on the States, on the relationship between thenational government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.
Does this AD involve a significant rule or regulatory action? 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 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, under 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. FAA amends Section 39.13 by adding a new AD to read as follows: