March 2008 Article.

SO WHAT DOES OUR USUAL MAINTENANCE FOR ZF579 ENTAIL?

 Weekly 'anti dets' (short for anti deteriorations) are normal practice for us. We carry this out on the electrical system, the hydraulic systems and other components. (normally engines too, by way of running them if fitted!).

This continues all year round no matter what the weather is doing. On a Lightning this exercise is absolutely imperative, to keep things in working order. 'Anti dets' generally entail plugging in 28Volt and 115 volt electrical ground supplies from our Houchin ground generator, and powering up the electrical buses and systems for 25-35 minutes. During this time all of the various electrical systems are exercised, such as fuel pumps, fuel cocks, aircraft radio/intercoms, navigation lights, cockpit lighting, ignition system, starting system, flaps, airbrakes, gun sights along with the hydraulic systems too.  At the same time, the canopy air driers have to be removed and treated weekly to keep the canopy glass interspaces dry and damp free. Other small off aircraft jobs have to be done too. Such as, maintaining the aircraft special batteries, repairing weather covers, checking tyre pressures, and taking fuel samples from the fuel tanks to make sure we don't get 'we fuel'.

Wet fuel? ......... Wet fuel occurs when a small percentage of water gets into the jet fuel from condensation build up inside the aircrafts' metal fuel tanks, caused by expansion and contraction. this can be quite a difficult thing to spot, since quite often water can become dissolved in the jet fuel, when stiring up the fuel pumps. first signs tend to be a naughty fuel indication system on a Lightning giving you inconsistent readings, or none at all! Regular fuel samples means a watchful eye can be kept, and any water build up can be eliminated early and quickly. So far on ZF579 we have had no issues with this, but we like to keep and eye out anyway. It's also a good way of checking for the presence of fuel microbes called "Cladosporium resinae" too. This nasty little black fungus can grow in aircraft fuel tanks, and leaving nasty slimes. Thankfully good quality jet fuel contains anti fungal chemicals to keep this little critter at bay!.  One of the questions we get asked is, "why don't you save money by putting heating fuel in the aircraft instead of expensive jet fuel?"

 Well asides from other issues with heating fuel, it doesn't contain the anti fungal inhibitors for this problem, and contains very high levels of sulfur, which is bad for seals and fuel components. Hence Jet fuel has to be used..

So here is what happens 52 weeks a year On a Saturday or Sunday morning for ZF579...

After waiting patiently all week the old tub sighs relief as the crew of 3-4 arrive on Saturday morning 9am....

- Donned up with overalls, we set about removing the weather covers and fitting the crew ladder

- Next, we open the battery bay and fit the Varley 24volt gel cell aircraft battery

-Next, 1 crew member opens the canopy, and fits the canopy lock, whilst the other uncovers the GPU (ground power unit)

-Plug in ground electrical supply

-Climb into cockpit and check all the switches.

-Next the GPU is fired up, aircraft electrical supplies are turned on

- A quick visual inspection of the flaps, airbrakes etc are done, and the green light is given to drop the flaps and open airbrakes.

-Aircraft 115volt supplies are turned on, and fuel contents gauges power up, where upon the fuel gauges are put through their full test ranges

- Once fuel contents gauging is happy,  fuel is transferred between wings for 5-10 seconds each way to test the fuel pumps are ok. The electrical cocks are put through their full range a few times to see that they are ok.

- Next, the starter circuits are livened (without the ignition), and the starter pumps are functioned several times.

- At this point various other systems like lights, cockpit illumination, the gun sight and radios are tested with head sets/helmets, before allowing the aircraft to settle down with power connected for 30 minutes.

- visual inspections are done, and the canopy driers removed. before power is turned off, to start the days restoration work at 10:00 a.m

- After another 9-10  hours hard work, ZF579 has to be put to bed again, with all her weather covers, to sleep for another week!!

And that's a day in the life of a ZF579 crew member. Week in , week out, come rain, wind, snow or sun.