Maintenance and engineering support for the RAF’s Rotary Hydraulic Arrestor Gear (RHAG) and its Portable Aircraft Arrestor Gear (PAAG).
The arrival of the UK’s new F-35 aircraft to its home at RAF Marham involved the development of major infrastructure including rebuilding the secondary runway and resurfacing the main runway. This all had to happen whilst the airfield remained fully operational for the Tornado Force based at the site.
One of the critical elements on a military fast jet runway is the arrestor gear, which is designed to stop aircraft in the event of an emergency landing or aborted take-off. In 2016 Marshall was awarded the contract for maintenance and engineering support for the RAF’s Rotary Hydraulic Arrestor Gear (RHAG) and its Portable Aircraft Arrestor Gear (PAAG).
When the refurbishment work at RAF Marham was being planned Marshall was called to install two RHAG systems on the rebuilt secondary runway to keep it fully operational whilst the primary runway was being refurbished and extended.
Checking the ground works prior to installation
The task was to define the ground levels for the equipment to be installed, to refurbish equipment sets held in storage, install them, and commission the systems into service in time for the runway coming into service.
This involved surveying the ground, identifying the correct locations, creating the installation drawings for the foundations to be designed to and liaising with the construction contractors prior to installing the equipment.
Marshall refurbished two RHAG systems, parts of which were several decades old, before installing them together with a newly designed and manufactured starter box.
Refurbishment on one of the arrestor drums which are integral to the RHAG system
The RHAG/PAAG systems operate in a similar way to the arrestor gear seen on an aircraft carrier. In the event of an emergency a steel wire cable is positioned across the runway and the hook fitted to a Typhoon aircraft is lowered by the pilot as the aircraft comes into land. On landing the hook catches on the cable and the system slows the aircraft down from the 120 knots it is likely to be doing on landing, to a safe stop.
The RHAG system consists of two horizontal drum wound tapes which tension the steel cable. Each drum drives a shaft fitted with paddles suspended in fluid whose viscosity reacts against the paddles when the cable is caught by the landing aircraft.
The RHAG arrestor drum installed
Just two months after the systems were installed and commissioned into service the first successful aircraft arrest was made following an aborted take-off with the aircraft brought safely to a stop.
Once the secondary runway was up and running in time for the arrival of the F-35s in the middle of 2018, Marshall removed the two RHAG systems from the main runway and took them to its Cambridge facilities for refurbishment, prior to re-installation when the main runway was completed.
RHAG setup and awaiting a "customer"
