Discussion
What events have caused this AD? Reports from the Luftfahrt-Bundesamt (LBA), which is the airworthiness authority for Germany, that the safety margins established into the design of the fuselage may not have been sufficient to sustain limit loads during certain maneuvers and during flight at certain speeds caused us to issue AD 2003-19-14, Amendment 39-13317 (68 FR 56152, September 30, 2003). AD 2003-19-14 requires the following:
--Modifying the airspeed indicators;
--Installing placards restricting flight speeds, prohibiting aerobatic maneuvers, and restricting load limits; and
--Incorporating revisions to the flight and maintenance manuals.
AD 2003-19-14 was issued as an interim action until the manufacturer completed further investigations into the effects of certain flight conditions on the fuselage structure and the development of corrective procedures.
What has happened since AD 2003-19-14 to initiate this AD action? The manufacturer conducted further static strength tests to verify the safety margin of the fuselage on the affected sailplanes. The results of these tests verified the following:
For Model G103 TWIN ASTIR sailplanes:
--Retain all flight limitation restrictions in AD 2003-19-14.
For Model G103 TWIN II sailplanes:
--Reinstate the original flight speed limitations and maneuver operations. For Model G103A TWIN II ACRO (utility category) sailplanes:
--Reinstate the original flight speed limitations and maneuver operations; and
--Allow only basic aerobatic maneuvers (spins, lazy eights, chandelles, stall turns, steep turns, and positive loops).
For Model G103A TWIN II ACRO (aerobatic category) sailplanes:
--Reinstate the original flight speed limitations except for rough air (VB) and maneuvering speeds (VA); and
--Allow only basic aerobatic maneuvers (spins, lazy eights, chandelles, stall turns, steep turns, and positive loops).
For Model G103C TWIN III ACRO sailplanes:
--Increase airspeed limits specified in AD 2003-19-14 but maintain a reduction from the original limitations; and
--Retain restrictions in AD 2003-19-14 on all aerobatic flights, including simple maneuvers, and cloud flying.
The manufacturer has also developed a modification for Models G103A TWIN II ACRO (aerobatic category) and G103C TWIN III ACRO sailplanes (aerobatic category). When this modification is incorporated, full acrobatic status is restored to these sailplanes.
What is the potential impact if FAA took no action? If not prevented, damage to the fuselage during limit load flight could result in reduced structural integrity. This condition could lead to loss of control of the sailplane.
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 GROB Models G103 TWIN ASTIR, G103A TWIN II ACRO, and G103C TWIN III ACRO sailplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on May 5, 2004 (69 FR 11111). The NPRM proposed to retain all the actions in AD 2003-19-14 for all Model G103 TWIN ASTIR sailplanes, remove Model G103 TWIN II from the applicability, and retain the aerobatic maneuver restriction for Model G103C TWIN III ACRO sailplanes. The NPRM also proposed to require you to revise the modification to airspeed indicators, install a revised flight speed reduction placard, and revise the flight and maintenance manual for certain Models G103A TWIN II ACRO, and G103C TWIN III ACRO sailplanes. Simple Aerobatic maneuvers were also proposed to be re-approved for Model G103A TWIN II ACRO sailplanes. An option for modifying the rear fuselage for Models G103A TWIN II ACRO and G103C TWIN III ACRO sailplanes that terminates the flight limitation restrictions for aerobatic maneuvers was also included in the NPRM.
Comments
Was the public invited to comment? We provided the public the opportunity to participate in developing this AD. We received no comments on the proposal or on the determination of the cost to the public.
Conclusion
What is FAA's final determination on this issue? We have carefully reviewed the available data and determined that air safety and the public interest require adopting the AD as proposed except for minor editorial corrections. We have determined that these minor corrections:
--Are consistent with 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.
Changes to 14 CFR Part 39--Effect on the AD
How does the revision to 14 CFR part 39 affect this AD? On July 10, 2002, the FAA published a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's AD system. This regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. This material previously was included in each individual AD. Since this material is included in 14 CFR part 39, we will not include it in future AD actions.
Costs of Compliance
How many sailplanes does this AD impact? We estimate that this AD affects 94 sailplanes in the U.S. registry.
What is the cost impact of this AD on owners/operators of the affected sailplanes? We estimate the following costs to accomplish the modifications to the airspeed indicators, flight limitations placards, and revising the flight and maintenance manual:
Labor cost
Parts cost
Total cost per Sailplane
Total Cost on U.S. operators
1 workhour x $65 = $65
Not applicable.
$65
$65 x 94 =$6,110
We estimate the following costs to accomplish the fuselage modification on 35 of the affected sailplanes in the aerobatic category:
Labor cost
Parts cost
Total cost per sailplane
30 workhours x $65 = $1,950
$5,307
$7,257
Regulatory Findings
Will this AD impact various entities? We have determined that this AD will not have federalism implications under Executive Order 13132. This AD 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.
Will this AD involve a significant rule or regulatory action? For the reasons discussed above, I certify that this AD:
1. Is not a "significant regulatory action" under Executive Order 12866;
2. Is not a "significant rule" under the 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.
We prepared a summary of the costs to comply with this AD and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include "AD Docket No. 2003-CE-35-AD" in your request.
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. The FAA amends 39.13 by removing Airworthiness Directive (AD) 2003-19-14, Amendment 39-13317 (68 FR 56152, September 30, 2003), and by adding the following new airworthiness directive (AD):