Discussion
The Luftfahrt-Bundesamt (LBA), which is the airworthiness authority for Germany, recently notified the FAA that an unsafe condition may exist on certain Grob Models G103 TWIN II and G103A TWIN II ACRO sailplanes. The LBA reports four instances of cracks in the fastening (knurled) nut at the rear
control stick.
These sailplanes are utilized extensively in flight instruction operations where the student is sitting in the front of the sailplane and the instructor is sitting in the rear of the sailplane. The instructor being able to utilize the rear control stick is imperative to the safety of these sailplanes.
If a cracked knurled nut at the rear control stick is not detected and corrected in a timely manner, loss of control of the sailplane during flight instruction operations could occur because the instructor may lose the ability to utilize the rear control stick.
Relevant Service InformationGrob has issued Service Bulletin 315-61/2, dated June 28, 1999, which specifies accomplishing preflight checks of the fastening (knurled) nut at
the rear control stick for cracks, and replacing the nut with one made of stainless steel, part number (P/N) 103-4205.03/2, either immediately or at a certain time period depending on whether cracks are found. The P/N 103-4205.03/2 knurled nut is included as part of Grob Service Bulletin 315-61/2, dated June 28, 1999.
The LBA classified this service bulletin as mandatory and issued German AD 1999-216/2, dated July 15, 1999, in order to assure the continued airworthiness of these sailplanes in Germany.
The FAA's Determination
This sailplane model is manufactured in Germany and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the LBA has kept the FAA informed of the situation described above.
The FAA has examined the findings of the LBA; reviewed all available information, including the referenced service information; and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.
Explanation of the Provisions of This AD
Since an unsafe condition has been identified that is likely to exist or develop in other Grob Models G103 TWIN II and G103A TWIN II ACRO sailplanes of the same type design registered for operation in the United States, the FAA is issuing an AD. This AD requires accomplishing preflight checks of the fastening (knurled) nut at the rear control stick for cracks, and replacing the nut with one made of stainless steel either immediately or at a certain time period depending on whether cracks are found.
Compliance Time of This AD
The replacement compliance time of this AD is presented in calendar time instead of hours time-in-service (TIS). Although cracking of the knurled nut at the rear control stick is a direct result of flight operations, the cracks could begin at any time and, if undetected, could cause the nut to break off and result in the inability to use the rear control stick. The cracks could initiate after 50 hours TIS on one sailplane, but not initiate until 500 hours TIS on another sailplane. For this reason, the FAA has determined that a compliance based on calendar time should be utilized in this AD in order to assure that the unsafe condition is addressed on all sailplanes in a reasonable time period.
Determination of the Effective Date of the AD
Since a situation exists 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 InvitedAlthough 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. 99-CE-68-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, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the FederalAviation 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: