ils systems

[empty pockets]

hey.

(to moderator, please move if this is the wrong section - ive posted it in tech. but am v.v.v.v. desperate for info!)

Hi,

I am an aero engineering student, and have an assignment whereby i have to compile a report on the maintenance of ILS systems and present my findings.

This is for a reliability and maintenance course module, so the emphasis is on this side of things rather than how it works. i have to include:

1] a history of the developments made to the system to increase reliability

2] some details of maintenance schedules / MTBF / failure rates etc.

3] example of how incorrect maintenance of the system contributed to a near miss incident or aircraft crash.

I have searched to web and so far havent found any relevant info. I would appreciate it if any of you guys could point me in the right direction.

Cheers,
Phil :)

[ICT_SLB]

Empty Pockets,
I see that your query hasn't had any answers. It's been some time since I worked proposals on aircraft for Flight Inspection (the overall maintenance of and verification of Navaids) but here are a few pointers. ILS checking is one of the most complex aspects of Flight Inspection. Companies that provide airborne equipment to do this include Sierra Systems of the US & Litton Systems of Missasauga, Canada. Two manufacturers of ILS are Rhode & Schwarz (Germany) and Harris (US).

Hope this helps.

[Shawn Coyle]

One of the more interesting aspects of ILS systems is how they are powered when Category II or III operations are in force. These low ceiling and visibility approaches obviously cannot afford to have even a second or two of off-line time. So obviously a backup power supply is needed, and there is a standby generator in nearly every ILS set up. However, the time to change over from mains to standby power takes some time, and this is too long a time during Category II or III operations. The solution is quite ingenious- run the system on the standby during those periods, with the changeover time to using the mains being measured in fractions of a second in the event that the standby suddenly goes down.

[spekesoftly]

Just to add to the above, I believe that most ILS systems are powered by a bank of batteries, that are constantly trickle charged from the mains. If the mains fails, then standby generators should start automatically, which take time before they are 'on-line', but the batteries ensure a 'no-break' power supply. As an added safeguard for CAT11/111 ops, the procedure is as described by SC.