A35041 - Safran Landing Systems Brake Wear Indicator Tube

A35041 – Safran Landing Systems Brake Wear Indicator (Hollow Rod)

Available now through the AirParts Aero marketplace.

Overview Section

The Safran A35041 is a high-precision Brake Wear Indicator (often referred to in maintenance manuals as a Regulator Tube or Wear Pin) designed for the carbon brake assemblies of the Airbus A330 and A340 series. Manufactured by Safran Landing Systems (formerly Messier-Bugatti-Dowty), this specialized hollow rod is the primary physical interface used to monitor the consumption of the carbon heat sink.1

In the high-energy braking environment of wide-body aircraft, the carbon discs gradually lose thickness. The A35041 is designed to retreat into the brake housing as wear occurs. By measuring the "protrusion" of this tube, maintenance technicians can determine the remaining service life of the brake stack without removing the wheel, ensuring the aircraft remains within the certified safety margins for every takeoff.

Key Features Section

• Hollow Rod Architecture: Engineered as a "tube" to provide maximum longitudinal stiffness with minimal weight—critical for reducing the unsprung mass of wide-body landing gear.

• Refractory Steel Construction: Fabricated from specialized high-temperature stainless steel capable of maintaining its dimensional stability even when the brake stack reaches temperatures exceeding 1,000°C.

• Corrosion Resistance: Specially treated to withstand the harsh chemicals found in runway de-icing fluids and hydraulic phosphate-ester fluids (Skydrol).

• High-Accuracy Measurement: Calibrated to the exact wear limits of the A330/A340 carbon brake specification, providing a reliable visual reference for ground crews.

• Thermal Isolation: The hollow design helps mitigate heat transfer from the carbon discs to the external measurement tip, protecting any associated electronic sensors or maintenance personnel.

• OEM Certification: Directly manufactured by Safran, ensuring precise fitment into the brake torque plate and alignment with the brake's internal regulator mechanism.

Technical Specifications Section

Aircraft Compatibility Section

The A35041 is the standard monitoring component for the wide-body Airbus fleet in the AirParts Aero network:

• Airbus A330-200/300: The primary wear indicator for both passenger and freighter (A330F) variants.

• Airbus A330neo: Compatible with the upgraded landing systems of the -800 and -900 variants.

• Airbus A340-200/300: Utilized on the original long-haul quad-jet fleet.

• Military Multi-Role Tanker Transport (MRTT): Used in the landing gear systems of A330-based military tankers.

Technical Applications & Safety

The A35041 is a "safety-of-flight" monitoring device. For a wide-body aircraft like the A330, the ability to stop during a Maximum Weight Rejected Takeoff (RTO) depends entirely on the thermal mass of the carbon brakes. If the A35041 indicates that the discs are worn beyond limits, the brake may not be able to absorb the energy of an RTO without failing.

Safety Warning: Brake wear measurements must only be taken with the Parking Brake SET. If the indicator rod is flush with the reference face, the brake is at its service limit. Operating with a flush indicator can lead to "over-stroke" of the brake pistons and potential hydraulic failure or fire.

Technical Engineering Insight

The engineering value of the Safran A35041 lies in its Thermal Expansion Management. In wide-body brakes, the temperature gradient is massive. The A35041 is engineered with a coefficient of expansion that matches the brake housing's guide bore. This prevents the "tube" from "thermal locking" or seizing, which would provide a false "safe" reading during a quick turn-around (QTA) where brakes have not yet cooled.

Furthermore, the A35041 serves as a mechanical "stop" for the internal wear regulator. By choosing the genuine Safran part through AirParts Aero, you ensure that the internal tolerances of the tube’s wall thickness and tip geometry meet the rigid standards required for Airbus Landing Gear Airworthiness.

Installation & Maintenance Addendum

1. Pin Protection: Ensure the indicator is not bent during wheel changes. A bent A35041 will bind in the torque plate, leading to inaccurate wear tracking.

2. Oxidation Check: Inspect the rod for "mushrooming" at the tip, which can occur after extreme braking events. A deformed tip should be replaced to maintain measurement accuracy.

3. Digital Integration: If the airframe is equipped with a Brake Wear Monitoring System (BWMS), verify the electronic sensor probe is correctly seated against the A35041 tube.