Discussion
What events have caused this AD? The Luftfahrt-Bundesamt (LBA), which is the airworthiness authority for Germany, recently notified FAA that an unsafe condition may exist on all GROB Model G120A airplanes. The LBA reports that a routine inspection of a Model G120A-I airplane found disbonding/cracking in the area between the vertical stabilizer main spar and nearby vertical stabilizer skin near the VOR (very high frequency omni directional range) antenna. A fleet-wide inspection of the Model G120A-I airplane fleet found one other Model G120A-I airplane with disbonding/cracking in the same area. The most likely reason for the disbonding/cracking was an incorrectly installed antenna support bracket, which caused permanent tension on the bonding seam. This resulted in disbonding/cracking in the area near the VOR antenna.
What is the potential impact if FAA took no action? Any disbonding/ crack in the area between the vertical stabilizer main spar and nearby stabilizer skin could result in possible structural failure. This failure could lead to difficulty in airplane flight control.
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 all GROB Model G120A airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on July 15, 2004 (69 FR 42360). The NPRM proposed to require you to repetitively inspect visually the area between the vertical stabilizer main spar and the nearby vertical stabilizer skin for any disbonding/crack; repair any disbonding/crack found; and calculate weight and balance after any repair.
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 airplanes does this AD impact? We estimate that this AD affects 6 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 do the inspection:
Labor cost
Parts cost
Total cost per airplane
Total cost on U.S. operators
1 workhour x $65 per hour = $65
Not applicable
$65
6 x $65 = $390
We estimate the following costs to do any necessary repairs that would be required based on the results of this proposed inspection. We have no way of determining the number of airplanes that may need this repair:
Labor cost
Parts cost
Total cost per airplane
20 workhours x $65 per hour = $1,300
The manufacturer covers under warranty and will supply any parts for the new U-profile assembly (antenna support bracket) consisting
of part numbers: 120A-2363.02; 120A-2364; and 120A-2365.
$1,300.
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 Ac
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 addresslisted under ADDRESSES. Include "Docket No. FAA-2004-18030; Directorate Identifier 2004-CE-13-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. FAA amends 39.13 by adding a new AD to read as follows: