Discussion
The FAA has recently received reports of several incidents of in-flight vibrations on Raytheon Models 35, A35, B35, and 35R airplanes (commonly referred to as Beech Models 35, A35, B35, and 35R airplanes). These incidents are unrelated to AD 94-20-04, Amendment 39-9032 (59 FR 49785, September 30, 1994), which currently requires, among other things, balancing the ruddervators (off the airplane) anytime the ruddervator is repaired or repainted on Raytheon 35 series airplanes. Of the 10 incidents since AD 94-20-04 became effective, 7 of the affected airplanes had ruddervators that were balanced and 3 of the affected airplanes had ruddervators that were out-of-balance.
Post-flight inspections of the airplanes involved in the above-referenced incidents have revealed cracked bulkheads and wrinkled skin in the aft fuselage; and broken spars, broken hinges, and bent skin on the stabilizers and ruddervators.
The Raytheon Models 35, A35, B35,and 35R airplanes are equipped with "V-tails" that have a narrow chord stabilizer without reinforcing cuffs. The FAA s preliminary investigation reveals the possibility of an unstable flutter mode in the 160 to 170 MPH range for the Raytheon Models 35, A35, B35, and 35R airplanes. This unstable mode is not likely to occur on other Raytheon airplane models with "V-tail" configurations.
The FAA's Determination
After examining the circumstances and reviewing all available information related to the incidents described above, the FAA has determined that AD action should be taken to prevent in-flight vibrations caused by the affected airplanes operating at excessive speeds, which could result in airplane damage and possible loss of control of the airplane.
Explanation of the Provisions of the AD
Since an unsafe condition has been identified that is likely to exist or develop in other Raytheon Models 35, A35, B35, and 35R airplanes of the same type design, the FAA is issuing an AD. This AD requires:
- fabricating a placard that restricts the never exceed speed (Vne) to no more than 144 miles MPH or 125 KTS IAS, and installing this placard on the instrument panel within the pilot s clear view;
- marking a red line on the airspeed indicator glass at 144 MPH (125 KTS);
- marking a white slippage mark on the outside surface of the airspeed indicator between the glass and case; and
- inserting a copy of this AD into the Limitations Section of the AFM.
Possible Follow-up AD Action
Raytheon is also reviewing the information related to the occurrences referenced in this AD and may develop a modification that, when incorporated, would eliminate the need for the speed restrictions required by this AD. The FAA will review any modification that is developed, determine whether it would eliminate the need for the requirements of this action, and then determine whether additional AD action is necessary.
Determination of the Effective Date of the ADSince a situation exists (possible loss of control of the airplane due to in-flight vibrations) 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 rule that 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 before and 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. 98-CE-55-AD." The postcard will be date stamped and returned to the commenter.
Regulatory Impact
The regulations adopted herein will not havesubstantial 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, 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: