AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Gates Learjet 35 and 36 Series Aeroplanes
AD/LEARJET 35/39 Forward Engine Beam Shear Web 5/2004
Applicability: Model 35, 35A, 36, and 36A aircraft, with serial numbers listed in Bombardier Service Bulletins 35/36-51-3, and 35/36-51-4 Revision 1 or Revision 2.
Requirement: 1. Accomplish a detailed inspection (using a probe) and a general visual inspection of the shear webs of the forward engine beams (including modification of the drag angles) for cracking in accordance with the Accomplishment Instructions of Bombardier Service Bulletin (SB) 35/36-51-3, dated 1 February 2001.
2. Following detailed probe inspection required by Requirement 1, accomplish the follow-on actions specified in following Requirements 2.a., 2.b., or 2.c., as applicable, in accordance with Accomplishment Instructions of SB 35/36-51-3.
- If the resistance measured during the inspection is less than 0.110 milliohm, repeat the inspections required by Requirement 1.
b. If the resistance measured during the inspection is 0.110 milliohm or more, but less than 0.150 milliohm, repair and modify the forward engine beam shear web in accordance with the Accomplishment Instructions of SB 35/36- 51-4 Revision 1, dated 2 August 2001, or Revision 2, dated 6 December 2001.
c. If the resistance measured during the inspection is 0.150 milliohm or more, repair and modify the forward engine beam shear web in accordance with the Accomplishment Instructions of SB 35/36-51-4 Revision 1 or Revision 2.
3. Following the general visual inspection required by Requirement 1, accomplish all of the applicable follow-on actions as specified in the Accomplishment Instructions of SB 35/36-51-3; except as specified as follows:
- If any crack opening is found that is more than 0.030-inch during the general inspection required by Requirement 1, accomplish the actions specified in paragraphs 2.C.(16)(a) and 2.C.(16)(b) of SB 35/36-51-3; repair per a method approved by the Manager, Wichita Aircraft Certification Office (ACO), FAA; and accomplish the terminating action specified in Requirement 4.
Gates Learjet 35 and 36 Series Aeroplanes
AD/LEARJET 35/39 (continued)
4. Modification of the shear webs by accomplishing all the actions specified in the Accomplishment Instructions of SB 35/36-51-4 Revision 1 or Revision 2; terminates the initial inspections required by Requirement 1 and the repetitive inspections required by Requirement 2.a.
Note 1: Where any service bulletin identified in this Directive specifies that the manufacturer may be contacted for disposition of certain repair conditions, repair per a method approved by the Manager, Wichita ACO, FAA.
Note 2: FAA AD 2004-03-08 Amdt 39-13452 refers.
Compliance: 1. At the later of the following times:
- Before the accumulation of 3,000 total flight hours; or,
b. Within 1,200 flight hours or 1 year after 13 May 2004, whichever occurs first.
2. a. At intervals not to exceed 1,200 flight hours.
b. Within the next 1,200 flight hours.
c. Before further flight.
3. At the times specified in the Requirement document.
a. Before further flight.
4. Terminates Requirements 1 and 2.a. inspections.
This Airworthiness Directive becomes effective on 13 May 2004.
Background: The manufacturer has received reports that the forward engine beam shear webs may develop cracks. The structural integrity of the engine beam shear web may be compromised depending upon the severity of the crack.
David Villiers
Delegate of the Civil Aviation Safety Authority 2 April 2004
The above AD is notified in the Commonwealth of Australia Gazette on 21 April 2004.
Overview
The Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) under the Civil Aviation Safety Regulations 1998 (CASR 1998) addresses an identified issue with the structural integrity of the forward engine beam shear webs of Gates Learjet 35 and 36 series aeroplanes. Specifically, the AD pertains to models 35, 35A, 36, and 36A with serial numbers listed in Bombardier Service Bulletins 35/36-51-3, and 35/36-51-4 Revision 1 or Revision 2. The directive was introduced to rectify the unsafe condition arising from potential cracking in these critical components. CASA's policy objective is to ensure the ongoing airworthiness of these aircraft by mandating specific inspection and repair actions to maintain the safety of operations. Compliance with the AD is required before the accumulation of 3,000 total flight hours, or within 1,200 flight hours or 1 year after 13 May 2004, whichever occurs first, and subsequent inspections must be conducted at intervals not to exceed 1,200 flight hours.
Scope and Application
This Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) applies specifically to Gates Learjet 35 and 36 Series Aeroplanes, including models 35, 35A, 36, and 36A, with particular serial numbers detailed in Bombardier Service Bulletins 35/36-51-3 and 35/36-51-4 Revision 1 or Revision 2. The directive mandates a series of inspections and potential repairs to the forward engine beam shear webs to address concerns of structural integrity due to possible cracking. The requirements include a detailed inspection and visual examination of the shear webs, with specific actions contingent on the resistance measurements obtained during the inspection. Depending on the results, the directive specifies whether further inspection, repair, or modification is necessary, with detailed instructions provided in the referenced service bulletins. The directive's compliance schedule stipulates that the initial inspection and subsequent actions must be completed before the aircraft accumulates 3,000 total flight hours or within 1,200 flight hours or 1 year after 13 May 2004, whichever comes first. Further inspections and actions are to be conducted at intervals not exceeding 1,200 flight hours or before further flight, as detailed in the directive. This AD is enforceable across the Commonwealth of Australia, ensuring adherence to safety standards for the specified aircraft models.
Key Provisions
The Airworthiness Directive (AD) pertains to Gates Learjet 35 and 36 Series Aeroplanes, specifically those with serial numbers listed in Bombardier Service Bulletins 35/36-51-3 and 35/36-51-4 Revision 1 or Revision 2. This directive mandates specific actions to ensure the safe operation of these aircraft, primarily focusing on the inspection and repair of the forward engine beam shear webs (section 1). To comply with this directive, a detailed inspection and general visual inspection of the shear webs must be carried out in accordance with the instructions provided in Bombardier Service Bulletin 35/36-51-3 dated 1 February 2001 (section 1). Depending on the resistance measured during the inspection, the actions specified in subsections 2.a., 2.b., or 2.c. must be followed. If the resistance is less than 0.110 milliohm, the inspection must be repeated; if it is between 0.110 and 0.150 milliohm, the shear web must be repaired and modified per the instructions in Bombardier Service Bulletin 35/36-51-4 Revision 1 or Revision 2; and if it is 0.150 milliohm or more, the same repair and modification process applies. The directive also specifies follow-on actions if any crack openings greater than 0.030-inch are found during the visual inspection, requiring specific repairs and terminating initial inspections as per the requirements outlined in Bombardier Service Bulletin 35/36-51-3.
The AD imposes several obligations on the entities it governs. Operators of Gates Learjet 35 and 36 Series Aeroplanes must ensure that the detailed and visual inspections are conducted by qualified personnel following the specified service bulletins. They must also ensure that any repairs or modifications are carried out in accordance with the instructions provided by the Federal Aviation Administration (FAA) Manager, Wichita Aircraft Certification Office (ACO). Failure to comply with these inspection and repair requirements may compromise the structural integrity of the aircraft, leading to unsafe conditions during flight.
The AD does not explicitly state any offences, penalties, or civil/criminal consequences for non-compliance. However, the failure to adhere to the requirements set out in the directive could potentially lead to civil aviation safety violations, which may result in enforcement actions by the Civil Aviation Safety Authority (CASA). Such actions could include fines, operational restrictions, or other regulatory measures intended to ensure compliance with airworthiness standards. The severity of these measures would depend on the specific circumstances and the extent of non-compliance.