It is hard to overemphasise the danger that small objects can be to the delicate workings of a jet engine if they are drawn into the mechanism. An item as small as a button can quickly render useless a multi-million-pound engine, damaging the delicate internal components. As such, aircrew clothing is carefully designed to minimise the danger of small, hard items such as buttons or zip fasteners becoming detached and lost inside an aircraft during maintenance. The coveralls issued to groundcrew use Velcro as the securing medium rather than buttons or zips for this very reason. The most common of the ground crew coveralls used by the RAF is a simple, plain green garment:
The coverall fastens from waist to throat using a long piece of Velcro, with a separate Velcroed tab to allow the coverall to be unfastened easily with greasy hands- just grab the tab and pull to start off the process of undoing it:
A degree of waist adjustment is provided by a pair of velcroed tabs at the rear waist of the coverall:
Pockets are provided in the form of a pair of thigh pockets, each with a square cut flap secured with the ubiquitous Velcro:
And a single angled breast pocket designed to carry pens in its three internal compartments:
This coverall was made by the Belgian firm of Seyntex, as can bee seen by the label sewn into the back of the garment:
The olive green coverall was not the only pattern used by the RAF, and we will be returning to these items of workwear next week with a similar but more flashy example.
Tales from the Supply Depot 
Ours were quite a bit different in style, there was a front two-way zipper covered with a velcro flap for example, two chest pockets and a flapped pen holder on the sleeve, but still no buttons. I wouldn’t be surprised if the full length velcro was to help get them off faster in the event of a fuel or chemical spill soaking them but the odds of jamming a zipper is pretty slim and in that sort of situation I’d be ripping the front open…velcro, zipper or not.
FOD is always a concern, buttons down the intake aren’t normally a really serious problem, turbine blades are still metal after all. Still, it’s not good for anything except air and fuel to be there and there is always a chance of a button damaging a blade to the point where it can set up some vibrations that can break it off and really mess things up, but some things are much worse than others.
A button or coin stuck behind a throttle lever or in a control linkage on the other hand, is a serious problem and has caused the loss of an aircraft before.
I always kept some small parts like fasteners or spare light bulbs in my coverall pockets, along with change for the canteen, as well as cigarettes and lighter, gloves, etc. but everything was in plastic bags, all pockets were secured and checked frequently, and my personal inventory was double checked each time I finished a job.