Events Leading to This AD
Recently, a Cessna Model 525 airplane was involved in an incident where the left main landing gear (MLG) collapsed during the landing roll even though cockpit indications showed that the MLG was in the normal down and locked position. Investigation revealed that loss of dry-film lubricant on the MLG trunnion bearings caused this incident.
Further investigation of the MLG of Cessna Model 525 airplanes indicates that this dry-film lubricant in the MLG trunnion bearings becomes inadequate over time. When these bearings are not properly lubricated, the roll pin that goes through the trunnion and bearing shaft fails, which causes the pin to back out of the bearing. This roll pin supports the entire MLG, so its failure then causes MLG collapse.
Applicable Service Information
Cessna has issued the following service information:
o Cessna Alert Service Letter SLA525-32-11, Revision 1, dated October 1, 1996, which includes procedures for inspecting the MLG trunnion pins for proper installation; and
o Cessna Service Bulletin SB525-32-08, Revision 1, dated October 1, 1996, which includes procedures for replacing the existing dry-film lubricated MLG trunnion slot bearings with sealed and self-lubricating bearings.
The FAA's Determination
After examining the circumstances and reviewing all available information related to the incident described above, including the above-referenced service information, the FAA has determined that AD action should be taken to prevent MLG collapse caused by trunnion bearing failure, which could result in loss of control of the airplane during landing operations.
Explanation of the Provisions of This AD
Since an unsafe condition has been identified that is likely to exist or develop in other Cessna Model 525 airplanes of the same type design, this AD requires repetitively inspecting the main landing gear (MLG) trunnion pins for proper installation, and either immediately or eventually replacing the existing dry-film lubricated MLG trunnion slot bearings with sealed and self-lubricating bearings. Only two inspections will be allowed before mandatory replacement of the MLG trunnion slot bearings. Accomplishment of the inspections required by this AD will be in accordance with Cessna Alert Service Letter SLA525-32-11, Revision 1, dated October 1, 1996. Accomplishment of the replacement required by this AD will be in accordance with Cessna Service Bulletin SB525-32-08, Revision 1, dated October 1, 1996.
Determination of the Effective Date of the AD
Since a situation exists (loss of control of the airplane during landing operations) that requires the immediate adoption of this regulation, it is found that notice and opportunity for public prior comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rulethat involves requirements affecting immediate flight safety and, thus, was not preceded by notice and opportunity to comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.
Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both beforeand after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket No. 96-CE-59-AD." The postcard will be date stamped and returned to the commenter.
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.
The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a significant regulatory action under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket (otherwise, an evaluation is not required). A copy of it, if filed, may be obtained from the Rules Docket.
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 USC 106(g), 40113, 44701.
39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: