AD/ROBIN/24 - Empennage Attach Bolts

Overview

The Civil Aviation Regulations 1998, as amended, address the need to ensure the safety and airworthiness of aircraft operating within Australia. Specifically, Part 39 - 105 of these regulations includes airworthiness directives issued by the Civil Aviation Safety Authority (CASA). The directives are designed to address specific safety concerns and ensure that aircraft meet the necessary safety standards. One such directive, AD/ROBIN/24, focuses on the empennage attach bolts of Robin Aviation Series Aeroplanes, particularly those in the R2000 Series. The directive was introduced to rectify issues identified through a Major Defect Report, which revealed inaccuracies in the specified torque values for the elevator and the absence of torque values for fin attach bolts in the Maintenance Manual. The directive mandates the verification of bolt torque, replacement or inspection of bolts that do not meet specified torque values, and inspection for fretting corrosion, all aimed at preventing potential safety hazards such as control interference or structural failure.

Scope and Application

The Civil Aviation Safety Authority (CASA) has issued an Airworthiness Directive (AD) under the Civil Aviation Regulations 1998, specifically within PART 39 - 105, mandating compliance with AD/ROBIN/24 for all models in the Robin Aviation R2000 Series. This directive applies to the empennage attach bolts, including elevator (stabilator) bearing attach bolts and fin attach bolts, requiring operators to verify and ensure these bolts meet specified torque values. Failure to comply may result in significant safety risks, such as fretting or fatigue failure of the bolts, which could compromise aircraft control and safety. This regulation applies to all operators of R2000 Series aeroplanes, mandating compliance at the next maintenance inspection following 14 August 1995 or when the aeroplane complies with AD/ROBIN/21, whichever comes first, and subsequently whenever a fin or elevator bolt is removed and replaced. This directive is enforceable throughout Australia and is overseen by CASA, ensuring adherence to the stipulated safety standards across all states and territories.

Key Provisions

The Civil Aviation Safety Authority's (CASA) Airworthiness Directive (AD) AD/ROBIN/24 pertains specifically to the Robin Aviation Series R2000 aeroplanes, focusing on the integrity and installation of empennage attach bolts (section 1). The directive mandates that the elevator bearing attach bolts on both the elevator and the fuselage, as well as the fin attach bolts, must be verified through a torque breakout check to ensure they meet specified torque values (section 1(a)). These values are critical to prevent potential issues such as fretting and fatigue failure of the bolts. Specifically, bolts with a 5mm diameter must be torqued to 44 in.lbs, 6mm diameter bolts to 80 in.lbs, and 8mm diameter bolts to 77 in.lbs (section 1(a)(b)(c)). In cases where the specified torque cannot be verified, the bolts must be removed, and either replaced with new bolts or inspected for cracking using approved techniques (section 2(a)). Additionally, the backs of the bearing brackets and the mating areas of the fuselage and elevator must be inspected for signs of fretting and fretting corrosion (section 2(b)). The directive also stipulates that elevator bearing (fuselage) bolts must be installed with the bolt heads on the bearing side and not inside the fuselage (section 3). Finally, the elevator and fin attach bolts must be torqued to the specified values (section 4). Compliance with AD/ROBIN/24 is mandatory and must be achieved by the next Maintenance Release issue after 14 August 1995 or when compliance with AD/ROBIN/21 is achieved, whichever occurs first (section Compliance). For subsequent inspections, compliance is required each time a fin or elevator bolt is removed and replaced (section Compliance). The directive remains in effect until the current Maintenance Manual (R2000 Service Manual Issue 1 Revision 3, October 1979) is revised or reissued and the updated torque values and bolt installation procedures are addressed (section Note). This ensures that all maintenance activities adhere to the correct specifications to maintain the airworthiness of the aircraft. Failure to comply with the provisions of AD/ROBIN/24 can result in significant safety risks. Insufficient torque on the elevator and fin attach bolts can lead to fretting of the attached items and fatigue failure of the bolts, which could compromise the structural integrity and control of the aircraft (section Background). The incorrect installation of elevator bearing bolts, as described in the IPC illustration, may also cause control interference, further exacerbating the risk. Therefore, adherence to these requirements is crucial to prevent potential accidents and maintain the safety standards required by CASA.