"Flight Testing" the Bell 525

[Boudreaux Bob]

Some discussion about the Bell 525 AFCS System and how it is being designed and tested.

'Flight Testing' the Bell 525 Relentless | Vertical Magazine - The Pulse of the Helicopter Industry (http://www.verticalmag.com/features/features_article/FlightTestingtheBell525Relentless#.U8nDDVaKMoE)

[GipsyMagpie]

The bit about tactile cues is interesting. When you think about how many aritificial cues are on fixed wing (stick shaker for example or g cues in aft stick) you have to wonder why its taken so long. Whilst I wouldn't blindly put them in without significant flight test why not have a cue for: incipient vortex ring, collective down cue on engine failure, lateral cues on reaching bank angle or collective cue on low height?

However some of the more modern afcs do sport some already when I think about it (power limit cue on Airbus Helicopter when you accel through Vy)

[Shawn Coyle]

The Gazelle (circa 1975) had a tactile cue in the collective called Intermediate Pitch Stop (IPS). You could pull as fast as you wanted to the change in spring force and not exceed any engine or transmission limits.
Tried it in a very light Gazelle when I was at Boscome Down - 60Kg of fuel when we wanted only 40Kg, no other seats in the machine - I pulled sharply up to the IPS and generated a 0.25G. Impressive response - the engine didn't miss a beat.
Not sure of what other tactile cueing would be really useful. My personal pet peeve is the very low forces to move the pedals in all helicopters. The best I've seen there was in a 4-axis autopilot version of the Polish W-3. It had a large breakout force on the pedals so that you could rest your feet on the pedals and keep heading hold engaged, but it took enough force to 'break' the heading hold that you knew you were doing it.

[Boudreaux Bob]

The Bell OH-58A with no hydraulics to the Tail Rotor Pedals surely met that requirement. After a while you got used to them but at first you thought they were just foot rests.

[Ian Corrigible]

The AW609 has tactile cueing on the power lever, and the CH-53K will have it on the sidestick cyclic controllers.

The tech has previously been matured on the UH-60Mu (http://www.nationaldefensemagazine.org/archive/2011/April/Pages/ArmySlowToAdaptFly-by-WireControlsforHelicopters.aspx) and on Boeing's AVMS (http://boeing.mediaroom.com/index.php?s=20295&item=2165)-equipped Little Bird testbed. It will also be trialled on an APAS (http://www.flightglobal.com/news/articles/us-military-to-test-bae39s-fly-by-wire-alternative-on-400769/)-equipped MH-47G next year (described by Flight as a "tactical cueing system...").

I/C

[Brilliant Stuff]

Shawn, can you elaborate please?

You want heavy pedals?

In my day job I want as light pedals as possible so I can change direction smoother, Out of 5hrs flying a day I only spend one hour in the cruise I hasten to add.

[bh412tt]

I flew a Bell 206 with a boosted tail rotor years ago, 58's and 206's are better un-boosted.............

[fijdor]

B206 are easier to fly without the boosted pedals. The "boost" makes them too sensitive in my opinion. A little bit of friction on the cyclic and collective and you get well balanced flight controls force wise.

JD

[spinwing]

Mmmm.....

....B206 are easier to fly without the boosted pedals. The "boost" makes them too sensitive in my opinion.....

Actually the problem with the over sensitive 'boosted' T/R on the 206 was with the mechanic who did not read the Bell M&O with regard to setting the correct friction preload ... this often happened because not all 206A's had the boosted T/R (S/n 409 onwards for a few a/c seems to stick in my memory for some reason) as a result quite a few did not know you had to adjust the pedal friction block (located in the panel just below the landing light) after certain maintenance inspections ... this friction adjustment was of course not necessary on the non boosted a/c which were in the majority thus many engineers did not even realise it was necessary ... it really made all the difference to the feel. :)

[John Eacott]

Enter the FAA:

Special Conditions: Bell Helicopter Textron, Inc. (BHTI), Model 525 Helicopters; Control Margin Awareness (https://www.federalregister.gov/documents/2018/06/06/2018-12076/special-conditions-bell-helicopter-textron-inc-bhti-model-525-helicopters-control-margin-awareness?utm_campaign=subscription%20mailing%20list&utm_source=federalregister.gov&utm_medium=email)



SUMMARY:

This action proposes special conditions for the BHTI Model 525 helicopter. This helicopter will have a novel or unusual design feature associated with the fly-by-wire flight control system (FBW FCS) in the area of pilot awareness of the control margins remaining while maneuvering the helicopter. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These proposed special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.
DATES:


Send your comments on or before July 23, 2018.




Partial quote, more on the linked page.

[JohnDixson]

One wonders when Part 29 and the associated advisory circular instructing as to methods of compliance, will address fly by wire technology, which has been around 25 years in the VTOL industry?

[whoknows idont]

Shawn, can you elaborate please?

You want heavy pedals?


Read his post again, he was talking about head hold mode.