Weather Radar Usage Boeing question

[M2dude]

Graybeard sir, I’m sure that you meant no offence/offense regarding the term ‘engineer’, but speaking as a UK CAA Licensed Engineer may I make a few points here?
In the 1980s It took me 7 years of study to gain licenses in TEN avionics subjects with the UK CAA. (I was no slouch, and passed every exam first time). The system has been simplified now, but it still requires a great deal of study and dedication. In an essay question, you’d be expected sketch and describe the workings of things like a radar Tx/Rx etc, and even if you passed this exam, you then had an oral examination with a CAA Surveyor who would quickly show you the door if you did not know your stuff. I know it’s only a word, but most technicians and mechanics have never had to go through all of this, and their level of knowledge and responsibility is not in the same league. Oh, and of course you need to stay up to date as far as modern avionics systems are concerned as well, the improvements in avionics systems since I gained my licenses are both fascinating and dramatic. Pappy’s explanation here is a little of an over simplification too I’m afraid Aircraft Line Mtce is an area, not a person, the guys who conceptualise and design the system are both Design Engineers. Guys, please do not pigeon hole people without knowing your pigeons. Moan over.
GB, Your point regarding the Tx/Rx itself being in a stable environment is of course correct, but as far as I recall my airline has no policy of routinely removing the scanner assembly for lubrication, and our MTBF is still extremely high. And just like the 767, the '400' and 777 systems are also only swithed on when you hit the button
Returning to the subject of radar system output power, I seem to remember that the old RCA system was about 60Kw peak output power, whereas the modern systems (Bendix etc) are around 100 Watts peak. As long as you are sitting BEHIND either system you are perfectly safe. (Can not recall any instances of ATC radar interference though). A point of interest regarding the older high power systems; if the aircraft in question flew at an extremely high cruise altitude, pressurising the waveguide system up to the scanner was absolutely essential. (You typically would used cabin air at the Tx/Rx end, and the fwd pressure seal would be maintained by a Mylar sheet over the flat-plate scanner). Even a small tear in this sheet would result in severe arc-over within the waveguide, rendering both radar systems useless. (I’ve seen the results, it’s as if someone has taken a welding torch to the inside of the waveguide). When the Bendix system was added as a retrofit to this aircraft, there was never another instance of waveguide arc-over.
I tend to agree with Capt Smithy; you are going to do more long-term harm to any system by regularly cycling the power, aircraft systems in general are far happier when they are left running, but particularly cycling a radar system on and off at cruise altitudes is never a good idea. Your radar system is there to help PROTECT you, why fly with your zipper undone?