B206 Long ranger sloping ground limitations
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B206 Long ranger sloping ground limitations
Hey All
Im looking for the official sloping ground limitation for the B206 Longranger as there is nothing in the flight manual..
Im looking for the official sloping ground limitation for the B206 Longranger as there is nothing in the flight manual..
Seem to recall 10 degrees to the left and 8 degrees right. Differences due to hanging left skid low in the hover, and jamming the left leg between cyclic and collective.
Nothing published for nose up (skids not designed for backwards stress on cross tubes) or nose down (BONK!!)
Nothing published for nose up (skids not designed for backwards stress on cross tubes) or nose down (BONK!!)
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RFM vs. Military
You won't find a slope operating limitation in the civilian Rotorcraft Flight Manual because there is no set limit for which it is permitted to operate the aircraft. It depends on each situation of gross weight, density altitude, center of gravity (fore/aft & lateral), and wind.
Bell considers* that the "limit" of slope operation is reached when, upon attempting a slope landing or takeoff, you reach the limit of control movement and therefore controllability. Since, based on the factors above, each situation may be different, there is no "limitation" published as to the slope of the landing/takeoff site.
When the U.S. military services publish a pilot's flight manual or operator's manual, they want rigid guidelines to establish permitted operations for their pilots,*and therefore slope limits in terms of degrees are published, which can be related to the actual slope of the landing site. Bell cooperated* with the military services and furnished numbers which can be considered conservative, i.e., could be accomplished under known or expected values of the parameters I listed in my first paragraph. [See *note below]
*In "Rotorbreeze," the quarterly-published Bell newsletter, there was a short article several years back discussing why Bell doesn't publish a slope "number" in the civilian manuals and why such a "number" is published in the military manuals. I tried to locate a link for you but haven't been able to as yet. If you will research the back issues of "Rotorbreeze" you may be able to find this article, I encourage you to do so and see what Bell had to say firsthand instead of relying on my memory of it. All the best...
Bell considers* that the "limit" of slope operation is reached when, upon attempting a slope landing or takeoff, you reach the limit of control movement and therefore controllability. Since, based on the factors above, each situation may be different, there is no "limitation" published as to the slope of the landing/takeoff site.
When the U.S. military services publish a pilot's flight manual or operator's manual, they want rigid guidelines to establish permitted operations for their pilots,*and therefore slope limits in terms of degrees are published, which can be related to the actual slope of the landing site. Bell cooperated* with the military services and furnished numbers which can be considered conservative, i.e., could be accomplished under known or expected values of the parameters I listed in my first paragraph. [See *note below]
*In "Rotorbreeze," the quarterly-published Bell newsletter, there was a short article several years back discussing why Bell doesn't publish a slope "number" in the civilian manuals and why such a "number" is published in the military manuals. I tried to locate a link for you but haven't been able to as yet. If you will research the back issues of "Rotorbreeze" you may be able to find this article, I encourage you to do so and see what Bell had to say firsthand instead of relying on my memory of it. All the best...
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I checked with my Bell person and got this reply:
There are no published sloping criteria for the 206 series. 407 is 10 degrees nose up and laterally, 5 degrees nose down. 206 has no limitations except make sure you can control the helicopter.
There are no published sloping criteria for the 206 series. 407 is 10 degrees nose up and laterally, 5 degrees nose down. 206 has no limitations except make sure you can control the helicopter.
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There are limits on the 206 as well, you'll hear a certain unpleasant noise coming from the mast if you exceeded the limits.
Last edited by jymil; 28th Sep 2014 at 21:49. Reason: Typo
Slope Limits
Goodpost Ian C, and an excellent article by James McCollough from the Bell Test Pilots Office.
Just to add an observation as to why I think those limits are worth posting in operators manuals: Hopefully, any pilot's checkout in a new vehicle includes slope landings, and those landings ought to be to the limits, so that the pilot becomes familiar with the aircraft behavior and control positions. Not all machines have similar limits and have varying amounts of control margin at those limits. In some cases, the limits are set by rules that may surprise. True story follows.
US Army requirement for UTTAS ( UH-60A ) was that the machine had to able to land on 12 degree slopes at any azimuth to the slope and laterally ( sideways onto slope ) at 15 degrees. Design gross Weight ( 16,500 lbs for the SA UTTAS version ). US Army guidance ( written in the Request for Proposal Handling Qualities section ) was that full control could be used, i.e., stick on the stop. For the 15 degree left wheel up slope landing, the cyclic control was hard on the left stick stop with the downhill wheel still a foot or a bit more in the air ( copilot graciously moved his leg ) so the collective was lowered to get that gear on the slope and that was determined to be in compliance with the requirement. Aside: at 15 degrees, there is real and appropriate concern for foliage and any obstacle on the uphill side as the rotor tip path is getting fairly low.
Now in the field, there is no way to eyeball a slope and determine if it is within your envelope or not, but if you have been trained to the envelope, you'll know, as you go down onto the slope, what to expect of your aircraft, and when to quit*. And you won't be placed in a position of not having been there before.
*There are a number of experienced and savvy aviators who peek into these pages, so inevitably, someone will ( correctly so ) remonstrate that the limits were written and tested to in zero wind, and what about that? I believe that observation is akin to the problem of not knowing what the real slope angle is, in the first place, and is another reason for thorough training.
( Minor point of interest to some: the lateral control range at the UH-60 rotorhead was set by this lateral slope landing requirement! )
Just to add an observation as to why I think those limits are worth posting in operators manuals: Hopefully, any pilot's checkout in a new vehicle includes slope landings, and those landings ought to be to the limits, so that the pilot becomes familiar with the aircraft behavior and control positions. Not all machines have similar limits and have varying amounts of control margin at those limits. In some cases, the limits are set by rules that may surprise. True story follows.
US Army requirement for UTTAS ( UH-60A ) was that the machine had to able to land on 12 degree slopes at any azimuth to the slope and laterally ( sideways onto slope ) at 15 degrees. Design gross Weight ( 16,500 lbs for the SA UTTAS version ). US Army guidance ( written in the Request for Proposal Handling Qualities section ) was that full control could be used, i.e., stick on the stop. For the 15 degree left wheel up slope landing, the cyclic control was hard on the left stick stop with the downhill wheel still a foot or a bit more in the air ( copilot graciously moved his leg ) so the collective was lowered to get that gear on the slope and that was determined to be in compliance with the requirement. Aside: at 15 degrees, there is real and appropriate concern for foliage and any obstacle on the uphill side as the rotor tip path is getting fairly low.
Now in the field, there is no way to eyeball a slope and determine if it is within your envelope or not, but if you have been trained to the envelope, you'll know, as you go down onto the slope, what to expect of your aircraft, and when to quit*. And you won't be placed in a position of not having been there before.
*There are a number of experienced and savvy aviators who peek into these pages, so inevitably, someone will ( correctly so ) remonstrate that the limits were written and tested to in zero wind, and what about that? I believe that observation is akin to the problem of not knowing what the real slope angle is, in the first place, and is another reason for thorough training.
( Minor point of interest to some: the lateral control range at the UH-60 rotorhead was set by this lateral slope landing requirement! )
We had a 206L which was modified for fire bucketing, and had an extra switch block attached to the cyclic for the "dump" function. it was on the lower left of the grip, just in reach of the little finger.
This extra block also reduced the left-to right slope limits because it hit my left leg well before the rest of the cyclic would normally do so.
This extra block also reduced the left-to right slope limits because it hit my left leg well before the rest of the cyclic would normally do so.
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One of the best reasons for no sloping ground limits is that the baseline helicopter configuration has no attitude indicator, so you have no way of obeying any angular limit.
Angular Limit
Hi Shawn,
Responding to your statement brings to mind an interesting fact about doing the higher angled slope landings in a non-skid type helicopter. Whether it is side-slope or nose up/down slope, the final resting attitude of the machine on its oleos, flat pitch, centered cyclic, will be greater by a couple of degrees ( 2- 3 in my experience ).
Thus, even though the slope may be exactly 12 or 15 degrees as measured by laying out a straight 2 x 4 and using a protractor, the final slope that the aircraft fuselage, rotor, and control system have to contend with is that much greater.
OEM gets credit only for the physical slope measurement.
Best,
John
Responding to your statement brings to mind an interesting fact about doing the higher angled slope landings in a non-skid type helicopter. Whether it is side-slope or nose up/down slope, the final resting attitude of the machine on its oleos, flat pitch, centered cyclic, will be greater by a couple of degrees ( 2- 3 in my experience ).
Thus, even though the slope may be exactly 12 or 15 degrees as measured by laying out a straight 2 x 4 and using a protractor, the final slope that the aircraft fuselage, rotor, and control system have to contend with is that much greater.
OEM gets credit only for the physical slope measurement.
Best,
John
Last edited by JohnDixson; 2nd Oct 2014 at 19:14. Reason: additional info/typo
