COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Grob G115 Series Aeroplanes
AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/GROB 115/12 and issues the following AD under subregulation 39.1 (1) of CAR 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.
AD/GROB 115/12
Amdt 1
Elevator Trim Tab 6/2000
Applicability: All Grob 115 aircraft which have not been modified in accordance with a scheme approved by the Authority.
Note 1: Aeronautical Engineers Australia Engineering Order EO4796/1 is an approved scheme for the purposes of this Directive.
Requirement: Clean the area around the Elevator Trim Tab Hinges including in the space between the Tab and Elevator.
Inspect using a x 10 magnifying glass around all Elevator Trim Tab hinges for cracking or debonding between the hinge tabs and the resin (See Figure 1). Not only the upper surface of the tab is to be examined, but close attention is to be paid to the junction between the sides/lower surface of the hinge flap and the forward edge of the elevator trim tab.
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
This AD may be carried out by a pilot. A copy of the AD is to be kept in the Flight Manual.
Note 2: The flap segment of the hinge attached to the trim tab runs under the upper surface of the tab.
Note 3: The debonding of the hinges appears as ‘cracking’ along the line joining the resin and hinge tabs. The growth rate of any cracking will be extremely fast.
Further, the crack progression will not be uniform nor similar to fatigue cracking. Therefore, any cracking found is indicative that the entire hinge has debonded.
Note 4: This inspection may be carried out by the pilot provided that a copy of this AD is available to him and a LAME has provided him with full instruction on where, what and how to look for any cracking. The pilot should also be aware of the possible consequences of partial or total separation of the elevator trim tab.
Compliance: Before the first flight of every day.
If operations of the aircraft are such that more than 5 hours are flown during the day, the inspection is to be carried out every 5 hours flight time until the end of flying for that day.
This Amendment becomes effective on 15 June 2000.
Background: On return from a flight a trim tab was found nearly departed from an aircraft.
Investigations found that the cause was bond failure between the hinges and the attaching resin. A further 6 tabs have since been found debonded, with one of the tabs having little more than 50 hrs TTIS. A loose trim tab can lead to flutter of the control surface. The manufacturer has been advised, and the initial issue of this AD was an interim solution pending development of a permanent solution.
Service experience with tabs which have been repaired/modified in accordance with the above scheme shows that it is effective in preventing this type of failure. This amendment excepts modified tabs from the requirement.
The initial issue of this Airworthiness Directive became effective on 6 May 1998.
Bernard Malcolm Hole
Delegate of the Civil Aviation Safety Authority 5 May 2000
The above AD is notified in the Commonwealth of Australia Gazette on 17 May 2000.
Overview
The Civil Aviation Regulations 1998 (CAR 1998), as amended, play a crucial role in ensuring the safety and airworthiness of aircraft in Australia. Part 39 of these regulations, which pertains to the Civil Aviation Safety Authority's (CASA) Schedule of Airworthiness Directives, is instrumental in addressing safety concerns through mandatory safety directives. The specific Airworthiness Directive AD/GROB 115/12, initially issued in 1998 and subsequently amended in 2000, was introduced in response to a critical safety issue identified in the Grob G115 Series Aeroplanes. This issue involved bond failure between the elevator trim tab hinges and the attaching resin, which posed a significant risk of trim tab debonding and subsequent flutter of the control surface, potentially leading to catastrophic outcomes. The directive mandates regular inspections and cleaning of the elevator trim tab hinges, requiring adherence to detailed procedures to ensure the integrity of the bonding and prevent future occurrences of this hazardous condition.
Scope and Application
The Airworthiness Directive (AD) AD/GROB 115/12 issued under the Civil Aviation Regulations 1998 applies to all Grob G115 series aircraft that have not been modified in accordance with a scheme approved by the Civil Aviation Safety Authority (CASA). This directive is mandated by the CASA delegate to address safety concerns identified with the elevator trim tab hinges on these aircraft. Specifically, the directive requires a thorough inspection and cleaning of the area around the elevator trim tab hinges to detect any signs of cracking or debonding, which could lead to a potentially unsafe condition. This inspection must be conducted by a pilot or a licensed aircraft maintenance engineer (LAME) who has been adequately instructed on the inspection process and its importance. The directive mandates that the inspection occurs before the first flight of every day and, if the aircraft is flown for more than five hours in a day, it must be repeated every five hours until the end of the flying day. Notably, this AD does not apply to aircraft whose elevator trim tabs have been modified under an approved scheme, such as Aeronautical Engineers Australia Engineering Order EO4796/1. The directive was initially issued on 6 May 1998 and was amended on 5 May 2000, with the amendment becoming effective on 15 June 2000.
Key Provisions
The Civil Aviation Regulations 1998, specifically under Part 39 - 105, detail the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives (ADs) for the Grob G115 series aeroplanes. This AD (AD/GROB 115/12) focuses on the elevator trim tab and mandates that all Grob 115 aircraft, which have not been modified under an approved scheme, must undergo certain inspections and cleaning to ensure the safety and airworthiness of the aircraft (section 1). The AD requires that the area around the elevator trim tab hinges be cleaned and inspected for any signs of cracking or debonding between the hinge tabs and the resin, using a magnifying glass (section 2). This inspection should be conducted before the first flight of every day and every 5 hours of flight time if the aircraft is flown for more than 5 hours in a day (section 3). The AD specifies that this inspection can be performed by a pilot, provided they have a copy of the AD and have received full instruction from a Licensed Aircraft Maintenance Engineer (LAME) (section 4).
The AD imposes specific obligations on the parties involved, including aircraft operators and pilots. Operators must ensure that all applicable aircraft are inspected according to the AD requirements before each flight and periodically during operations if the flight time exceeds 5 hours (section 5). Pilots are required to conduct or oversee the inspections, with the guidance of a LAME, and to keep a copy of the AD in the Flight Manual (section 6). Additionally, any modifications to the elevator trim tab hinges must be carried out under an approved scheme, such as Aeronautical Engineers Australia Engineering Order EO4796/1, to ensure that the modifications are effective in preventing bond failures (section 7).
Failure to comply with the AD may result in serious safety implications, as bond failures in the elevator trim tab can lead to control surface flutter, which can compromise the aircraft’s safety. The AD does not specify particular offences, penalties, or consequences for non-compliance, but non-compliance with ADs can lead to enforcement actions by CASA, which may include grounding the aircraft until the required actions are taken. The safety and operational integrity of the aircraft depend on strict adherence to these directives (section 8).