The ACES is the best portable unit I have used. It requires no additional battery or ships power and no blade targets, if you have ever been half way through a tracking flight, particularly with a Bell 412 and had a target come off, you will know how frustrating this is and expensive. To set it up on a single engine machine really is only five minutes work and no magnetic pick ups with brackets. I have found the digital read out of blade separation very accurate and combined with a clock angle can quickly tell you if you have a blade problem or worn bearings.

Problems can also be traced with the spectrum analysis which by way of harmonics can show up 2 per rev and 4 per rev. I recently ran a spectrum on an Alison C30 in real time by just holding the velometers against the engine. I have tried the rest, this Model 2020 unit has NOT had to be sent back time and time again because its U/S.