- Joined
- Jan 13, 2016
- Messages
- 891
- Reaction score
- 356
In some applications, like helicopter rotors, the part is so critical that it has a specified service life, after which it's replacement is mandatory. This in spite of maintenance procedures that might include Maga Flux
Rotors on real helicopters are maintained very well with well documented cases and reasons as why and when rotors or props are to be changed regardless of passing any visual inspection. You mentioned "Maga Flux" testing - I knew what you meant was magnetic flux testing whereas the metal is magnetized and areas that show any magnetic filed loss is usually due to corrosion, blow holes etc. and the piece being testing is either tagged for replacement or trending begins as to life expectancy (L10). Gear boxes are the biggie for the rotors - vibration analysis goes a long way as to other non-destructive testing - looking for up to the 5th harmonic of a gear mesh frequency is key to determining the health of a particular gear - that is one test that if collected data is analyzed properly where you don't necessarily change out a gearbox at a predetermined time but rather when anomalies are detected via vibration analysis.
Would you see any need to replace a propeller that still looks fine, but has reached a certain age or number of flights? It seems like plastic is less likely to hide emerging defects like a metal helicopter blade could,
As for our Phantom and the life of the rotating elements of which we have few, to include - props, motors and bearings. The brushless motor types will very likely out live the bird or the hobby when used under, and in normal operating condiotions (flying in extreme weather conditions - like very high or freezing air ambient temperatures, in rain or snow or at full throttle all the time - despite what others might say - is not considered normal flying conditions - LOL).
The motor bearing on the other hand will wear out long before the motor does. The props or rather the hubs for same will wear out when considering the loss of clamping due to thermal expansion and contraction of same over time. The life (L10) of these rotating elements I can't say definitively how long they would last................however, and having said that, there are maintenance steps we can take to ensure longer life and identify pro-actively any up coming issues (PdM - Predictive Maintenance).
To list a few -and please anyone add any you feel are a good part of the plan for maintenance of rotating elements......
1. Turn the motors by hand periodically and make note of any restrictions or points where during rotation they feel like they are jamming (this will help determine bearing condition).
2. Use a flashlight and even a magnifying glass to inspect motor windings through the openings on top of the motor - look for discolouration of the copper windings (dark spots indicate the motor has gotten hotter than its allowable temperature rise and the insulating varnish on the copper coils/winding is compromised/worn) - time to replace the motor. Any burning smell is a great warning of same with regard to loss of insulation varnish on coils - so take a sniff once in a while - lol. It's your bird and you should be able to recognize any odd noises from it that could be bearing wear - motor issues or even prop issues that require a closer inspection!
3. If you have been flying or landing in areas where there is a lot of contaminants (dust, sand etc.) - use one of those cans of compressed air you have for the computer cleaning and blow out and around the motor windings or use a small vacuum cleaner for same or both simultaneously - again through the opening at the top of the motor housing. Good idea to do that periodically regardless of landing area.
4. Feel the motor frames one at a time to detect by touch or better yet with a thermometer to identify any one which may be experiencing higher heat than the other after a flight. It is a good idea to get a baseline on temperatures and log that into that maintenance book I know you all have - so you can trend and compare temps over time.
5. Checking those nasty plastic prop hubs - visual checks again with a magnifying glass and a light source inside the hub and around it. Plastic hides infancy cracks very well and a lot won't show until under load. If you suspect a poor fit or a problem prop hub a good check is to fill the hub with hot water then to see if any water leaks from the hub exterior - the hot water will help open up any infancy cracks. Or use dyed water to quickly see if there are any leaks present. Another method is to ever so slightly bend the props and have a good look around the hub for evidence of any cracks.
6. Prop blades - visual inspection is the obvious - any scratches or nicks - replace the prop - keep in mind if your prop has contacted the ground on landing and the motor has stalled but still powered up- the load on the prop hub is increased significantly and can cause a crack in the hub even if the prop shows very little damage (inspect your motor also if that happens - see item 2)
7. Stick to OEM parts for rotating elements and don't do a lot or even any modifications to your Phantom body - mess with the structures natural frequency and you may create vibration problems you don't want - we all know vibration is not a friend of rotating elements - especially bearings.
Using our own senses as to sight, sound, smell and touch will help tremendously when it comes to maintaining our Phantoms - especially the rotating elements.
Ok, a little long winded and I apologize for that - hope it helps some out - safe happy flying!
Last edited: