Bell 206: JetRanger and LongRanger
You can detect its effect if you enter auto gently with a fixed cyclic position. Initially the nose drops as the tailplane is unstalled in the negative sense. Then the spoiler disrupts the airflow over the top of the tailplane and the nose rises again.
Also the horizontal stabiliser presents a nice big flat surface to push on as the aircraft descends which adds to the nose forward attitude. Probably haven't made that comment as clear as I could have but hey ho.
And I should be clearer in that it is the rotor that flaps forward or backward when you lower or raise the lever - how much the fuselage follows that is subject to other factors (control rigging/mixing for example).
Equally the resulting fuselage attitude in steady state descent/climb/auto is much more affected by other aerodynamic features such as the tail stab as Evil Twin points out.
Equally the resulting fuselage attitude in steady state descent/climb/auto is much more affected by other aerodynamic features such as the tail stab as Evil Twin points out.
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206b noise
Looking for some help from all you 206 experts out there....
I manage and fly a 'newer' 206B3 out of the local airport. It is always well maintained to 135 standards and has under 4000TT. If it matters, it has Van Horn T/R blades and a Lord Elastomeric bearing which are a few years old.
I've now had two airplane mechanics (mostly unfamiliar with rotorcraft workings) from different airports randomly walk up and tell me they've heard my helicopter come and go hundreds of times over the past few years, but recently there is a high pitched whine coming from back which they hadn't heard before. They both said you can't hear it until the helicopter has passed by them, so they are facing the back of the aircraft. Nothing has changed that I can think of which would account for the new noise. My first thought was possibly a hangar bearing going bad, but they were all checked out during my recent annual inspection. Any chance it's the T/R gearbox trying to warn me before it fails? The chip detector is clean....
I didn't pay much attention to the first guy, but now two?! I'm not overly concerned but am starting to get curious. Thank you in advance for your thoughts.
I manage and fly a 'newer' 206B3 out of the local airport. It is always well maintained to 135 standards and has under 4000TT. If it matters, it has Van Horn T/R blades and a Lord Elastomeric bearing which are a few years old.
I've now had two airplane mechanics (mostly unfamiliar with rotorcraft workings) from different airports randomly walk up and tell me they've heard my helicopter come and go hundreds of times over the past few years, but recently there is a high pitched whine coming from back which they hadn't heard before. They both said you can't hear it until the helicopter has passed by them, so they are facing the back of the aircraft. Nothing has changed that I can think of which would account for the new noise. My first thought was possibly a hangar bearing going bad, but they were all checked out during my recent annual inspection. Any chance it's the T/R gearbox trying to warn me before it fails? The chip detector is clean....
I didn't pay much attention to the first guy, but now two?! I'm not overly concerned but am starting to get curious. Thank you in advance for your thoughts.
The Bell 206B T/R gearbox is simple and very reliable. If the chip detector is clean and the oil is clear, nothing to worry about.
The Van Horn blades are known to be quieter than the Bell metal blades; could this be the difference they are noticing?
The LORD T/R trunnion STC is a great improvement but would have no effect on noise type/level.
Fly Safe, Always
The Van Horn blades are known to be quieter than the Bell metal blades; could this be the difference they are noticing?
The LORD T/R trunnion STC is a great improvement but would have no effect on noise type/level.
Fly Safe, Always
Join Date: May 2017
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I'd concur with the two previous posts. If the T/R and/ or gearbox are not producing any "secondary" indications such as vibrations, metal or excessive heat, I'd look elsewhere, and as "formerlongbox" suggests, eyeball the engine. Another suggestion; years back I had an issue with an oil cooler blower or "squirrel cage". The impeller had somehow received a slight deformation to a couple of "vanes", which set up what was described as a shrill whistle at full RPM. Hard to pinpoint as it couldn't be heard from the front or on the ground close up as the engine and rotor noise masked it pretty well, but it could be heard from a distance aft and away from the helicopter. Good luck.
Uusanl noise
The fuel pump is a good call, I have also had this, easy to check, remove and turn the spline, if it’s tight that’s your boy. I also had a bad bearing in the accessory gearbox, sounded like turbine, sadly only way to eliminate is swap out.
Have chased many "unique" sounds over the years. FYI: Sometimes how a person hears the noise and how sound travels doesn't always indicate where on the aircraft it may come from.
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Update on 206b noise
Update on the noise they were hearing....
#3 bearing in the gearbox was cracked and eventually started making quite a bit of metal. Engine is repaired and sounds normal again.
#3 bearing in the gearbox was cracked and eventually started making quite a bit of metal. Engine is repaired and sounds normal again.