Bell 525 Relentless
Join Date: Sep 2007
Location: USA
Posts: 601
Likes: 0
Received 0 Likes
on
0 Posts
Interestingly, this article says Bell claims they achieved a 200kt forward speed with their 525 testing. Pretty impressive for a conventional helo.
Third Bell 525 Joins Flight-test Fleet | Business Aviation News: Aviation International News
Third Bell 525 Joins Flight-test Fleet | Business Aviation News: Aviation International News
Interestingly, this article says Bell claims they achieved a 200kt forward speed with their 525 testing. Pretty impressive for a conventional helo.
Third Bell 525 Joins Flight-test Fleet | Business Aviation News: Aviation International News
Third Bell 525 Joins Flight-test Fleet | Business Aviation News: Aviation International News
Vne is far less about aerodynamics and more about component life as well as practicalities - no point having a limit that can only be achieved in a 3000 ft/min dive!
Join Date: Nov 2007
Location: Massachusetts
Age: 67
Posts: 172
Likes: 0
Received 0 Likes
on
0 Posts
I've kept my eyes open and haven't seen much info about the FBW system in the 525 other than it's triple redundant and a derivative of Bell's tilt rotor work.
Does anybody have any more information about it? I'm curious about what kind of software/computing redundancy is used (I did some work with Boeing and with the safety cert guy from the 777 and was impressed that they used 3 dissimilar processor chips to avoid computer architecture bugs causing issues among other strategies).
What kinds of strategies are used to avoid RF induced interference? (thinking of the UH60 issues flying near radio/tv broadcast towers).
Is it safe to assume that the hydraulic system is conventional, and only the command of the servos is FBW?
Maybe a pointer to any articles/white papers on the design of the FBW system?
Thanks!
Does anybody have any more information about it? I'm curious about what kind of software/computing redundancy is used (I did some work with Boeing and with the safety cert guy from the 777 and was impressed that they used 3 dissimilar processor chips to avoid computer architecture bugs causing issues among other strategies).
What kinds of strategies are used to avoid RF induced interference? (thinking of the UH60 issues flying near radio/tv broadcast towers).
Is it safe to assume that the hydraulic system is conventional, and only the command of the servos is FBW?
Maybe a pointer to any articles/white papers on the design of the FBW system?
Thanks!
Join Date: Oct 2002
Location: 1 Dunghill Mansions, Putney
Posts: 1,797
Likes: 0
Received 1 Like
on
1 Post
This paper from EASA's 8th Rotorcraft Symposium held in December 2014 provides some insight into the FBW system: Model 525 Relentless advanced fly-by-wire – The pilot’s safety advantage
I/C
I/C
Join Date: Aug 2009
Location: Around
Posts: 36
Likes: 0
Received 0 Likes
on
0 Posts
Page 4 of Model 525:
Newman and Lambregt closing comment – “overall FBW and envelope protection have prevented accidents and saved lives. In the past 15 years, there have been 27 stall
accidents in commercial transport operations with 848 fatalities –
not one was a FBW airplane”
Errrm, AF447 ?
Newman and Lambregt closing comment – “overall FBW and envelope protection have prevented accidents and saved lives. In the past 15 years, there have been 27 stall
accidents in commercial transport operations with 848 fatalities –
not one was a FBW airplane”
Errrm, AF447 ?
Join Date: Sep 2007
Location: USA
Posts: 601
Likes: 0
Received 0 Likes
on
0 Posts
FAR 29.695 requires single fault tolerance capability for flight critical boosted control systems such as hydraulic actuators used for rotor blade pitch. Single fault tolerance would mean having two independent actuation systems capable of performing the same function, where in the event one experiences loss of function for any (credible) failure mode, the other will be capable of continuing to perform the function as required for safe flight. This means every half of a single fault tolerant system must be able to operate independent of the other half, from end to end.
Having functional redundancy in just part of a system is helpful, but does not usually meet full system functional fault tolerance requirements.
Having functional redundancy in just part of a system is helpful, but does not usually meet full system functional fault tolerance requirements.
Apology from Helihub-When
With fake outrage the editor of the Helihub website generated an open letter "shaming" Bell for promoting the 525 as an EC225 replacement (see below):
Now that the latest EC225 info on the latest fatal crash points to a design deficiency and the 225 is looking at another extended grounding at best (despite Airbus's press releases saying nothing to see here all is fine just a mechanic screw up), Helihub should apologize to Bell and request Airbus to apologize to all maintainers. I know they won't because they would loose all that "advertising" (payoff) money.
The Sultan
19 May, 16, Source: HeliHub.com
Respected aviation media outlet Aviation International News has run a story quoting Bell saying that their new 525 Relentless helicopter, currently under development, is a “Super Puma replacement”. Helihub.com has requested validation of the quote from Bell, but despite opening our email within one minute of sending it over four hours prior to us publishing this piece, the company has failed to respond. We cannot believe that Aviation International News would publish wording they cannot stand by, so we have to assume the quote is correct.
How can a manufacturer of the standing of Bell stoop so low as to malign a competitor aircraft at a time when there is a significant safety focus on the AS332/H225 following the accident near Bergen in Norway on 29th April?
Respected aviation media outlet Aviation International News has run a story quoting Bell saying that their new 525 Relentless helicopter, currently under development, is a “Super Puma replacement”. Helihub.com has requested validation of the quote from Bell, but despite opening our email within one minute of sending it over four hours prior to us publishing this piece, the company has failed to respond. We cannot believe that Aviation International News would publish wording they cannot stand by, so we have to assume the quote is correct.
How can a manufacturer of the standing of Bell stoop so low as to malign a competitor aircraft at a time when there is a significant safety focus on the AS332/H225 following the accident near Bergen in Norway on 29th April?
The Sultan
Join Date: Jan 2015
Location: Europe
Posts: 111
Likes: 0
Received 0 Likes
on
0 Posts
Truth is the 525 is maybe a 332L replacement. The Helihub point is more that the 525 should be marketed on its merits.
Airbus never said a mechanic screwed up as you put it. You are just showing your prejudices by that interpretation.
Airbus never said a mechanic screwed up as you put it. You are just showing your prejudices by that interpretation.
Join Date: Sep 2007
Location: Birmingham
Posts: 244
Likes: 0
Received 0 Likes
on
0 Posts
Absolutely, if you follow the other threads here on that one you will see that there are seven potential scenarios, some inter-related. The suggestion that this whole thing was caused by the omission of a safety pin suffers from the a total lack of evidence to date but relies on other people's interpretations of a rather vague AH statement. In addition the chances of it being caused by a single event such as this seem very small at this stage (fatigue has been found in a gear stage and is being further investigated). Have a heart for the people who worked on this machine who are going through a very difficult time
Airbus aimed everyone at a loss of a support link and away from the transmission which led to people focusing on installation issues (i.e. the fault of the maintainer) so I stand by my statement. As to seeking marketing advantage from a competitor's real or perceived issue, Airbus is the master. So no tears here if they are on the receiving end.
The Sultan
Helihub: Still waiting for the retraction.
The Sultan
Helihub: Still waiting for the retraction.
Join Date: Jan 2015
Location: Europe
Posts: 111
Likes: 0
Received 0 Likes
on
0 Posts
Airbus aimed everyone at a loss of a support link and away from the transmission which led to people focusing on installation issues (i.e. the fault of the maintainer) so I stand by my statement. As to seeking marketing advantage from a competitor's real or perceived issue, Airbus is the master. So no tears here if they are on the receiving end.
The Sultan
Helihub: Still waiting for the retraction.
The Sultan
Helihub: Still waiting for the retraction.
Why would that be a hiccup, megan? The salient points of that article.
Seems a prudent approach.
Is it "service history" that you feel is the location of hiccup in this case?
Therefore it is necessary to determine the structural factors of safety and operating margins such that the probability of structural failures due to the application of loads during FBW FCS malfunctions is not greater than that found with rotorcraft equipped with traditional flight control systems. To achieve this objective and to ensure an acceptable level of safety, it is necessary to define the failure conditions and their associated frequency of occurrence.”
With the FBW FCS system, fully operative strength requirements of Part 29 need not be investigated beyond limit conditions “when it can be shown that the rotorcraft has design features that will not allow it to exceed those limit conditions.” In evaluating failure conditions shown not to be extremely improbable, loads assume failures begin in 1g level flight and include pilot corrective actions. The special conditions also provide that special periodic inspections, daily checks and pre-flight inspections may be used in lieu of failure-detection and -indication systems, but “must be limited to components that are not readily detectable by normal detection and indication systems and where service history shows that inspections will provide an adequate level of safety.”
Join Date: May 2016
Location: USA
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
It does seem to be late in the program, but most recent TCs have a number of special conditions. I think at least the first special condition has been applied to all the Part 25 fly-by-wire airplanes. Not so sure about the other.
Certguy
Certguy