Robinson R44 Series Helicopters
AD/R44/10
Amdt 1
Main Rotor Blade 14/98 DM
Applicability: Model R44 helicopters, serial numbers 0002 through 0486, with main rotor blades part number (P/N) C016-1 installed.
Requirement: 1. Inspect the main rotor blade skin around both inboard trim tab alignment rivets as follows, referring to Figure 1 of this Directive:
(a) Remove all paint around both rivets, exposing an area of approximately ¾ inch in diameter, at the inboard trim tab on the top and bottom of each blade (four places per blade). Use 180 grit or finer abrasive paper, followed by 600 grit or finer paper to eliminate course sanding marks. Sand only in a spanwise direction. Do not use chemical paint strippers.
(b) Inspect the blade skin around the rivets on the blade upper and lower surfaces (four locations) using a dye penetrant method.
Note 1: Chordwise cracks in the paint up to 2 inches long which are located along either inboard or outboard edge of the trim tab are acceptable.
(c) Clean the sanded areas prepared with 111-trichloroethane or methyl ethyl ketone and then apply clear lacquer to seal the unpainted areas.
Note 2: Do not bend the inboard main rotor blade tabs from their present position or utilise them for any subsequent blade tracking adjustment.
2. Thereafter, using a 5-power or higher magnifying glass, visually inspect the upper and lower blade skin surfaces around the inboard trim tab rivets (four locations) for cracks.
3. Replace main rotor blades P/N C016-1 with main rotor blades P/N C016-2.
Note 3: Robinson Service Bulletin SB-28, dated 18 June 1998, refers.
Note 4: Installation of a set of main rotor blades, P/N C016-2, constitutes terminating action for the requirements of this Directive.
Note 5: FAA Priority Letter AD 98-22-16 refers.
Compliance: 1. Unless already accomplished, within 5 hours time in service after November 4 1998.
2. Before the first flight of each day, or at intervals not to exceed 5 hours time in service, whichever occurs first.
3. Replace the main rotor blade before further flight if a crack, other than as described by Note 1, is found when inspected as per requirement 1 or 2, otherwise replace before 1 December 1998.
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
This amendment becomes effective on 4 November 1998.
Background: The FAA received a report of an incident in which a pilot heard a loud noise and felt severe vibrations while hovering, resulting in a forced landing. Upon inspection, a crack was found in a main rotor blade that started at the mid-span inboard trim tab and ran chordwise to the spar where it turned along the spar for about an inch. The crack originated from a trim tab alignment rivet hole in the blade skin.
Subsequent investigations revealed that the manufacturing process utilised to drill the trim tab alignment rivet holes in the main rotor blade skin can allow a fatigue crack to originate at these holes and propagate in the skin. This condition, if not corrected, could result in failure of the main rotor blade and subsequent loss of control of the helicopter.
This amendment adds a requirement to replace the affected main rotor blades. Examination of the cracked main rotor blade has indicated that a crack may develop in any of the affected blades. As it has not been possible to determine how quickly the crack progressed, it is not possible to maintain the airworthiness of the blade through inspection. It is therefore necessary to remove the affected main rotor blades from service.
The initial issue of this Airworthiness Directive became effective on 5 June 1998.
Overview
The Civil Aviation Regulations 1998, which were enacted by the Parliament of the Commonwealth of Australia, include a provision for Airworthiness Directives to ensure the ongoing safety of aircraft in Australian airspace. One such amendment, AD/R44/10, was introduced on 4 November 1998, in response to a reported incident involving a Robinson R44 Series Helicopter where a pilot experienced a loud noise and severe vibrations during hovering, leading to a forced landing. The source of the issue was identified as a crack in a main rotor blade that originated from a trim tab alignment rivet hole, a problem stemming from the manufacturing process used for these helicopter blades. This Airworthiness Directive mandates the replacement of specific main rotor blades (part number C016-1) with new blades (part number C016-2) in Robinson R44 helicopters with serial numbers ranging from 0002 through 0486, to prevent the risk of blade failure and subsequent loss of control. The policy objective behind this measure is to ensure the continued airworthiness of affected helicopters by mitigating the risk of blade failure due to fatigue cracks.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39 - 105, mandate airworthiness directives through the Civil Aviation Safety Authority to ensure the safety and reliability of aircraft in Australian airspace. This legislation applies to Robinson R44 Series helicopters with serial numbers ranging from 0002 to 0486, specifically those equipped with main rotor blades part number C016-1. The directive demands a rigorous inspection and, if necessary, the replacement of the main rotor blades to prevent potential catastrophic failure due to fatigue cracks originating from the trim tab alignment rivet holes. This requirement must be met within 5 hours time in service after the amendment’s effective date of 4 November 1998, and before the first flight of each day, or at intervals not exceeding 5 hours time in service, whichever occurs first. The replacement of the blades must be completed by 1 December 1998 unless a crack is detected during inspection, in which case the replacement must occur before further flight. This directive is applicable nationally, ensuring compliance across all states and territories within the Commonwealth of Australia.
Key Provisions
The main sections of this Airworthiness Directive (AD) require Robinson R44 Series Helicopters, specifically those with serial numbers ranging from 0002 to 0486 and equipped with main rotor blades part number (P/N) C016-1, to undergo an inspection of the main rotor blade skin around the inboard trim tab alignment rivets (section 1). This includes removing paint to expose the blade skin, inspecting for cracks using a dye penetrant method, and sealing the sanded areas with clear lacquer (section 1(a)-(c)). After this inspection, a visual inspection for cracks using a magnifying glass is mandated (section 2). Finally, the directive requires the replacement of the main rotor blades P/N C016-1 with P/N C016-2 (section 3). The directive also includes compliance requirements, stipulating that inspections and blade replacement must be completed within a specific timeframe after the AD's effective date (section Compliance).
The obligations imposed by the AD include the requirement for operators and owners of the specified Robinson R44 helicopters to perform the detailed inspections and, if necessary, replace the main rotor blades. The inspections must be performed before the first flight of each day or at intervals not exceeding five hours of time in service, whichever comes first (section Compliance 2). If a crack, other than those described in Note 1, is found during inspection, the blade must be replaced before further flight. If no such cracks are found, the blade replacement must occur before 1 December 1998 (section Compliance 3). Operators must also ensure that the inboard main rotor blade tabs are not bent and are not used for any blade tracking adjustments (section 1 Note 2).
Failure to comply with this AD can result in serious safety implications, as non-compliance may lead to the failure of the main rotor blade and subsequent loss of control of the helicopter. The AD itself does not specify any penalties or enforcement actions, but non-compliance could potentially lead to enforcement actions by the Civil Aviation Safety Authority (CASA) under the Civil Aviation Act 1988 or the Civil Aviation Regulations 1988. Such actions could include fines, suspension or revocation of aircraft certificates of airworthiness, or other regulatory actions deemed necessary by CASA to ensure compliance and maintain airworthiness standards.