Hi there,
I've only got about 300 hrs on 500s but have had a number of tail rotor problems:
Chips, short circuits and a Total loss of tail rotor control due to an unusual mechanical failure, (If you fly 500s regularly, I urge you to read the accident/incident report here so you can check on this particular problems:
http://www.atsb.gov.au/publications/...200505332.aspx
I like the info that Giovanni has put in. That's good stuff.
Here's my two cents worth...
The chip detector is a magnetic plug with two elements. When the elements are bridged by metal particles, the circuit is made and the T/R chip light illuminates on the master caution panel.
Sometimes, new components will wear down whilst they are 'bedding in' and some small particles will float and be caught. It is not unusual.
Some chip detectors have a thing called 'Fuzz Burn' which will put a larger electrical charge through small particles and disintegrate them. The reason is that small particles are normal wear and tear and if they're small enough to be burnt off using Fuzz Burn, then they are not really anything to worry about. (Fuzz Burn will sometimes cause the warning light to come on momentarily and then, once the item is burnt off, will extinguish).
If the chip is too big to be burnt off using Fuzz Burn, then the circuit will be made and the light will activate. This indicates significant chip in the system. Put the aircraft on the ground!
On one occassion, the T/R chip light was constantly illuminated but more dimly than other warning lights.
What to do?
1. Check chip detector - remove detector, look for chips, (save any chips on a piece of sticky tape folded over itself so that it can be used for analysis by engineers), clean chip detector, replace.
2. Do ground run for 30 mins.
3. Check chip detector again as in step 1. If no chips, then it's your decision to continue. Seek maintenance advice and then make a decision based on received information, flight manual/maintenance manual recommendations, your judgement, your comfort level and level of risk. (If in doubt, stay on the ground!)
4. If light is still on, get someone to earth/ground the connecting wire whilst you watch the caution panel. If the light illuminates brightly, then that's what it will look like if you have a chip. If the circuit is broken (when your helper ceases earthing/grounding the wire) and the light returns to its less bright condition, then you have a short circuit in the system.
What does this mean if the above happens? Well, the light will stay on because of the short circuit but if you get a chip, then the light will burn brightly. If you decide to continue, then remember that you'll have to keep an eye on the brightness of the warning light (which you can confirm by activating the press to test function of the MCP and comparing the different levels of brightness). Be aware of the difficulty in seeing warning lights when sunlight is shining directly on the MCP.
It means you can get to your destination with relative confidence in the chip detection system but you do so at your own peril. You must be happy that you can tell when you have a real indication compared to the constant false indication.
I was happy to fly the aircraft (solo without passengers) to the next destination which, at my insistance, was an airport that could do maintenance and fix the short circuit. The bosses were happy with the decision and so was I. T/R gearbox replaced, circuitry replaced, aircraft good to go.
Once, when I was flying Chinooks, we got a chip light, landed and pulled the detector. A bearing race had collapsed and the chips were over 1cm long (1/3 inch). One of them had a serial number stamped on it. NO JOKE!
Safe flying
CB