Engineering Section

Lightning Association Engineering

As will have been seen from ‘About Us’, the Association owns, in conjunction with a number of member shareholders, an operational Lightning F.6, XR724, and a large amount of spares and ground equipment. The aircraft is currently kept on the former RAF Binbrook airbase, which is now in private ownership. Much of the history of XR724, its preparation for flight and its final flight into RAF Binbrook are covered in back issues of the Lightning Review. The purpose of this page on the Association website is to introduce the engineering team and to let you know what projects have been undertaken recently.

XR724 groundcrew; from the left, Iain Leishman, Les Overton, Pip Sweetman, Alan Watson, John Watson, Andy Thirde, Dennis and Jessica Wood.

The main members are:
Pip Sweetman, ex-RAF Binbrook Engine Technician.
Les Overton, ex- RAF Binbrook Airframe Technician, 6 years in ASF from 1980-1986.
John Watson, an electrical engineer.
Dennis Wood, an HGV driver and ex RAF Binbrook civilian worker, and his daughter Jessica, who turns her hand to any odd jobs.
Andy Thirde, another driver and general helper.
Mike Smith, another general helper who works mainly with computers.
Iain Leishman, also Membership Secretary and a graduate engineer.
Last but by no means least is Matthew Johnson, who is mostly responsible for the sheeting and application of WD40 to keep the worst of the weather out!

We have replaced the A/C Alternator which is driven by the air turbine gearbox (ATGB). We had discovered that the rotol valve had tripped, and this stops air being delivered to the ATGB, which prevents normal A/C and D/C electricity supply to the aircraft with engines running. The rotol valve trip was caused by the quill drive from the ATGB to the alternator shearing; this shearing was caused by the main bearing in the alternator collapsing and seizing in the unit. With the drive sheared, the load on the output of the ATGB is reduced, and as a consequence of this the ATGB speeds up. At a predetermined speed, the rotol valve will trip to prevent the ATGB overspeeding and damaging itself.

We located a serviceable spare Alternator and quill drive and these were fitted over 2 weekends. Being a Lightning, the removal and fitting of the alternator could be best imagined as trying to get a full 5 litre oil can through a letter box from the wrong side. Bear in mind that once one pair of hands are in the access panel, no more can go in and you can see even less! This task was also carried out during the winter, which made it even more fun (I think it was fun). On the following engine run, it was discovered that although there was an electrical output from the alternator, no supply was reaching the cockpit. Further investigation by John Watson and his father Alan traced the fault to a voltage regulator, one of the many black boxes in the spine. This unit was replaced, and electrically the systems appear serviceable; however checks are ongoing.

At this point, I would like to pay tribute to Alan Watson, who sadly died just as we were nearing the end of these tasks, and I think that those of you who were at the evening reheat run certainly saw the benefits of his efforts. It was a fitting farewell for a valued member who is very much missed.

The Association has also purchased a PALOUSTE, basically a small jet engine on a trailer, which can be plugged in to the aircraft main air system to drive the ATGB. This will allow us to test the aircraft electrical systems without the need to start XR724’s engines; a saving in aircraft fuel and, more importantly, it conserves the Avpin stock. The palouste can also deliver the correct amount of airflow to start other aircraft, so if any other group is interested in borrowing the unit, I am sure something can be arranged. Thanks here go to Matthew, who stripped the trailer down to its last nut and bolt and rebuilt it and painted it prior to the engine with its batteries and fuel supply being mounted.

The current engineering task, which is almost at rebuild completion, is the overhaul of the No.2 reheat pipe, removed from XR725 (in Charles’s garden!) last April.

The purpose of this project is to give us a serviceable unit to fit to XR724, as investigation has shown that the nozzle on the unit in ‘724 has jammed shut and that some of the nozzle rollers appear to be out of their tracks and guides. It is probably this problem which is preventing the No.2 engine accelerating above 92%. To prevent any damage to the engine or structure, this engine is currently only run at idle, just to move the oil around and to keep the system ticking over.

The unit removed from ‘725 has been completely stripped down and we have undertaken the following:

All the nozzle rollers were corroded and seized. There are 16 of these rollers, and each roller contains 14 needle rollers - that means that 224 of these have had to be stripped and all corrosion (about 20 years worth) cleaned off and then re-assembled.

All control rods and operating linkages into and out of the Air Motor Control Unit and into the Air Motor itself, as well as the Air Motor, were corroded and seized.
John Watson has had the job of removing the nozzle drive ring and removing and cleaning 254 ball bearings by hand. Well done, John, the ring can now be turned with one finger.

All the screwjacks were corroded and seized, and again they have been stripped cleaned and lubricated ready for rebuild.

We are now on the rebuild stage of this project and then we can get the unit swapped and set up in XR724, after which we can have reheat on No.2 engine once again.

This page will be updated regularly and I hope to add some pictures of the reheat pipe project shortly.

The reheat 'diamonds' light up the pan during a night engine run at Binbrook.

Thanks to everyone for your continued support. For anyone with a technical question or who wants to know more about XR724, engine runs etc, or who wants to volunteer to work on the aircraft, I can be contacted as below.

Les Overton.
Tel : 01472 507566

E-mail your questions to info@lightning.org.uk