Discussion
What events have caused this AD? Reports of chafing and/or arcing of the fuel boost pump wiring inside the fuel pump reservoir that supplies fuel to each engine on Cessna Model 441 airplanes caused us to issue AD 2002-09-13, Amendment 39-12746 (67 FR 31117, May 9, 2002). AD 2002-09-13 requires you to: (1) do a one-time inspection of the electrical wiring going to the fuel boost pump reservoir and the boost pump wiring inside the reservoir for chafing or damage, and (2) repair or replace the wiring as necessary.
These actions are required in accordance with Cessna Conquest Service Bulletin No.: CQB02-1R1, Revision 1, dated April 22, 2002.
What has happened since AD 2002-09-13 to initiate this action? Further analysis of this situation reveals that:
--The actions required by AD 2002-09-13 should also apply to Model F406 airplanes;
--The inspection should be repetitive; and
--Improved design wire harnesses and fuel boostpumps should eventually be installed as terminating action for the repetitive inspections.
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 Cessna Models 441 and F406 airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on October 21, 2002 (67 FR 64568). The NPRM proposed to supersede AD 2002-09-13 with a new AD that would require repetitive inspections of the Models 441 and F406 airplanes fuel boost pump wiring inside and outside the boost pump reservoir for chafing or damage and replacement of the wiring and fuel boost pump, as necessary, and require eventual installation of an improved design wire harness and fuel boost pump as terminating action for the repetitive inspections.
How will this action relate to the FAA's aging commuter-class aircraft policy? The FAA's aging commuter aircraft policybriefly states that when a modification exists that could eliminate or reduce the number of required critical inspections, the modification should be incorporated. This policy is based on the FAA's determination that reliance on critical repetitive inspections on airplanes utilized in commuter service carries an unnecessary safety risk when a design change exists that could eliminate or, in certain instances, reduce the number of those critical inspections. In determining what inspections are critical, the FAA considers (1) the safety consequences of the airplane if the known problem is not detected by the inspection; (2) the reliability of the inspection.
What is the potential impact if FAA took no action? This condition, if not detected and corrected, could result in arcing within the wing fuel storage system. Such a condition could lead to ignition of explosive vapor within the fuel storage system.
Was the public invited to comment? The FAA encouraged interested persons toparticipate 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: Remove Warnings Following Compliance to the Proposed AD
What is the commenter's concern? The commenter, for clarity and completeness, requests that the AD call out removing the warning placards after compliance with Cessna Conquest Service Bulletin No.: CQB02-1, Revision 2, dated October 7, 2002.
What is FAA's response to the concern? We concur with the commenter and for clarity and completeness will change the final rule AD action to incorporate this change.
Comment Issue No. 2: Validity of the 200-Hour Time-in-Service (TIS) Recurrent Inspection Requirement
What is the commenter's concern? The commenter states that the 200-hour TIS recurrent inspection is not necessary because the commenter's specific aircraft is 24 years old and has more than 7,900 hours TIS and inspection finds only minor chafing of onewire. Further, the commenter states that the 200-hour TIS recurrent inspection increases the likelihood of creating fuel leaks because of the constant reopening and resealing of the fuel boost pump panels. The commenter disagrees with the 200-hour TIS recurrent inspection requirement. Because the commenter did not request an alternative time, we infer that the commenter wants the repetitive inspection deleted from the AD.
What is FAA's response to the concern? We do not concur. Initial investigation revealed harnesses and fuel boost pump leads with virtually no chafing, some with minor chafing, and several with excessive chafing that appeared to have been arcing. Additionally, all of the above conditions were found on aircraft with relatively low TIS to high TIS. The 200-hour TIS recurrent inspection is necessary to assure continued airworthiness of repaired wire harnesses.
We are not changing the final rule AD action as a result of this comment.
Comment Issue No. 3: Allow the Aircraft To Be Operated With Greater Than 80 Pounds or 12 Gallons of Fuel in Either Wing Tank Instead of Replacing the Wire Harnesses and Fuel Boost Pumps
What is the commenter's concern? The commenter states that the wire harness is submerged in fuel when 80 pounds or 12 gallons of fuel remain in each wing tank. The commenter requests that the proposed AD allow the aircraft to be flown with greater than 80 pounds or 12 gallons of fuel remaining in either wing tank instead of replacing the wire harnesses and fuel boost pumps that exhibit chafing of the wire harness.
What is FAA's response to the concern? We do not concur. There are two wire harnesses in each wing tank, each with the potential for chafing and subsequent arcing if not corrected. The potential for arcing within the fuel tank continues to exist until replacing or repairing both sources of possible arcing. The request to allow operation with 80 pounds of fuel remaining in either tank only assures the fuel boost pump lead wires to remain covered with fuel. Engineering evaluation has determined that safe operation without repaired or replaced wire harnesses requires approximately 300 pounds to assure both wire harnesses are submerged in fuel.
We are not changing the final rule AD action as a result of this comment.
Comment Issue No. 4: Replace the Fuel Boost Pumps
What is the commenter's concern? The commenter states that the fuel boost pump wire harness is the reason for the AD action and the fuel boost pumps remain in an acceptable operating condition. The commenter disagrees with replacing the fuel boost pumps. The commenter states that the problem is with the fuel boost pump wire harnesses and replacement of the fuel pumps is an undue and unnecessary burden on the operators.
What is FAA's response to the concern? We do not concur. Chafing has been found to occur on both the fuel boost pump lead wires and the wire harness extending from the fuel boost pump housing towing structure on several aircraft with varying times-in-service.
We are not changing the final rule AD action as a result of this comment.
Comment Issue No. 5: Correct Cost Estimate for Replacing the Wire Harnesses and Fuel Boost Pumps
What is the commenter's concern? The commenter disagrees with the estimated cost of replacing the wire harnesses and fuel boost pumps. The commenter justifies disagreement with cost data from one service center.
What is FAA's response to the concern? We do not concur. The cost estimate associated with the cost impact with the proposed AD has been coordinated with Cessna, and found to be valid.
We are not changing the final rule AD action as a result of this comment.
Comment Issue No. 6: Adequacy of the 1,200-Hour TIS Phase 11 Inspection
What is the commenter's concern? The commenter requests that, once the wire harnesses have been replaced and the fuel boost pumps have been replaced or repaired, the inspection criteria on the 1,200-hour TIS Phase 11 inspection include specific instructions to inspect the wire harnesses and fuel boost pump leads for chafing and security. The commenter further states that including specific instructions to inspect the wire harnesses and fuel boost pump leads would assure continued airworthiness of the harnesses and boost pump leads.
What is FAA's response to the concern? We do not concur. The Model 441 Maintenance Manual was revised on July 1, 2002, with specific instructions to visually inspect all wire bundles/electrical components in the fuel storage area. Cessna and FAA agreed that inspection of these areas would occur every 600 hours TIS or 24 calendar months, whichever occurs first, to coincide with the general electrical wiring and component inspection interval. The FAA will monitor the service history and take further rulemaking action if it shows that normal maintenance practices are not eliminating the problem.
We are not changing the final rule AD action as a result of this comment.
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 the changes discussed above and minor editorial questions. We have determined that these changes and minor corrections:
--Provide the intent that was proposed in the NPRM for correcting the unsafe condition; and
--Do not add any additional burden upon the public than was already proposed in the NPRM.
Cost Impact
How many airplanes does this AD impact? We estimate that this AD affects 370 airplanes in the U.S. registry.
What is the cost impact of this AD on owners/operators of the affected airplanes? We estimate the following costs to accomplish the inspection:
Labor cost
Parts cost
Total cost per airplane
Total cost on U.S. operators
8 workhours x $60 per hour = $480
None
$480
$480 x 370 = $177,600
For Model 441 airplanes, we estimate the following costs to accomplish the replacements:
Labor cost
Parts cost
Total cost per airplane
8 workhours x $60 per hour = $480
$13,101
$480 + $13,101 = $13,581
For Model F406 airplanes, we estimate the following costs to accomplish the replacements:
Labor cost
Parts cost
Total cost per airplane
8 workhours x $60 per hour = $480
$7,558
$480 + $7,558 = $8,038
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 the national 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 reasonsdiscussed 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 39.13 by adding a new AD to read as follows: