Discussion
What Events Have Caused This AD?
The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom, recently notified FAA that an unsafe condition may exist on all British Aerospace Model HP.137 Jetstream Mk.1, Jetstream Series 200, Jetstream Series 3101, and Jetstream Model 3201 airplanes. The CAA reports that the steering jack piston rod failed on one of the affected airplanes while in service. The CAA determined that the failure of the piston rod was caused by fatigue cracking on the piston rod end fitting. Fatigue cracking was caused by applying excessive torque to the steering jack piston rod end fitting during assembly.
The safe life limit for the steering jack piston rod is currently 45,000 ground-air-ground (GAG) cycles. Failure of the above-mentioned steering jack piston rod occurred at 2,132 GAG cycles. Because of the possibility that excessive torque had been applied to the steering jack piston rod during assembly, the safe life limit for this part has been reduced.
What Is the Potential Impact if FAA Took No Action?
This condition, if not detected and corrected, could result in failure of the steering jack piston rod. Such failure could lead to loss of steering control of the airplane during takeoff, landing, and taxi operations.
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 British Aerospace Model HP.137 Jetstream Mk.1, Jetstream Series 200, Jetstream Series 3101, and Jetstream Model 3201 airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on January 27, 2003 (68 FR 3832). The NPRM proposed to require you to inspect the steering jack piston rod for cracks and replace if necessary; measure the torque setting of the steering jack piston rod end fitting and stop bolt; and measure the thickness of the tab washers. The NPRM also proposed to require you to calculate a new safe life limit for the steering jack piston rod based on the results of the proposed inspection and the proposed measurements.
Was the Public Invited to Comment?
The FAA encouraged interested persons to participate in the making of this amendment. We did not receive any comments on the proposed rule or on our determination of the cost to the public.
FAA's Determination
What Is FAA's Final Determination on This Issue?
After careful review of all available information related to the subject presented above, we have determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. We have determined that these minor corrections:
--Provide 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 inthe NPRM.
How Does the Revision to 14 CFR Part 39 Affect This AD?
On July 10, 2002, FAA published a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs FAA's AD system. This regulation now includes material that relates to special flight permits, alternative methods of compliance, and altered products. 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.
Cost Impact
How Many Airplanes Does This AD Impact?
We estimate that this AD affects 250 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 accomplish the inspection:
Labor cost
Parts cost
Total cost per airplane
Total cost on U.S. operators
1 workhour x $60 = $60
No parts required
$60
$60 x 250 = $15,000
We estimate the following costs to accomplish any necessary replacements of the steering jack piston rod that would be required based on the results of the inspection and/or measurements. We have no way of determining the number of airplanes that may need such replacement:
Labor cost
Parts cost
Total cost per airplane
8 workhours x $60 = $240
$5,300
$240 + $5,300 = $5,540
Compliance Time of This AD
What Will Be the Compliance Time of This AD?
The compliance time of this AD is "within the next 90 days or 200 ground-air-ground (GAG) cycles after the effective date of this AD, whichever occurs first."
Why Is the Compliance Time Presented in Calendar Time and Operational Time?
Failure of the steering jack piston rod is only unsafe during airplane operation; this condition is not a result of the number of times the airplane is operated. The cause of the unsafe condition is the result of incorrect torque settings used on the steering jack piston rod end fitting during assembly. We have no way of determining when the unsafecondition occurred on the affected airplanes. For this reason, the FAA has determined that a compliance time based on calendar time and operational time should be utilized in this AD in order to assure that the unsafe condition is not allowed to go uncorrected over time.
Regulatory Impact
Does This AD Impact Various Entities?
The regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.
Does This AD Involve a Significant Rule or Regulatory Action?
For the reasons discussed above, I certify that this action (1) Is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under 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. A copy of the final evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.
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: