169 crash

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FatBoy1971
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Re: 169 crash

Postby FatBoy1971 » Thu Nov 15 2018, 11:40

flyhuey wrote:Here is a learning opportunity.


Some interesting questions here, flyhuey. I'm not sure of all of the answers, and I'm not sure of the ones that I will try and answer.

So, just wondering, about Antitorque Rotor efficiency hovering rearward versus forward?
I don't think that the anti torque rotor itself will care whether the wind is on the nose or the tail, however, the whole tailboom would want to weathercock, to put the nose into wind.

Wondering about Class 1 takeoff, what were the Winds above the Stadium Wall/Overhanging Roof?
Not sure of the winds above the stadium, that should be addressed in the accident report. Are you thinking that the tail rotor could have entered vortex ring state? It certainly is something to consider.

Wondering at what forward airspeed airflow over the Vertical Fin would improve directional control during LTE or complete loss of T/R Thrust?
Don't know. Is there anybody on here that is AW169 rated that can tell us?

Wondering in a foot ball stadium that size, could a Pilot taxi to the furthest end, downwind, then takeoff with some forward airspeed into the wind, with a steep rate of climb, up and over the roof and if one or both engines fail take it as it comes?
Then it most likely wouldn't be a Performance Class 1 (PC1) departure (as defined by ICAO). If the critical power unit failed after the defined point after takeoff it may result in a forced landing (therefore Performance Class 2) into the stands/seats. The owner of the aircraft possibly specified that he wanted the aircraft to be operated PC1 for departures and landings, and therefore a safe landing for both the aircraft and occupants. PC1/2 is only dealing with a failure of the critical power unit, nothing else.

Wondering when doing a Class 1 Takeoff, would a Pilot's control input be so precise as to land spot on or possibly with a bit of forward flight and overshot the spot?
I practice these in the simulator for the larger aircraft, and on grassed areas in smaller twins (eg. AS355, BK117). With proper emergency training I would say the answer to your question is "yes", precise landing to the spot or safe area.

Wondering how must thrust is required to hover vertically to say 500 feet OGE, then how much thrust would be required to overcome the Drag footprint of the entire fuselage whilst hover backwards, OGE?
Not sure, it would depend on airspeed backwards. I would hazard a guess and say "negligible" extra power required to overcome the parasite drag at slow speeds.

So, is that takeoff the best performance model and the safest takeoff option? Again, not all Multi-engine helicopters and not all Multi-engine helicopter Pilots use that takeoff.
The CAT A/PC1 profile is the one that the aircraft manufacturer has tested as part of the certification process. The aircraft that I currently fly has PC1 and PC2 profiles for clear areas, ground level helipads and elevated helipads. Again PC1 is only for a safe landing following the failure of the critical power unit at any time during the departure or approach. Do I fly PC1 for all of my departures, no. Why not? Because the client specifies PC2.

Where is it in the Regulations governing a specific takeoff profile to use?
Client driven?

Anybody else able to add to the discussion?
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Twistgrip
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Re: 169 crash

Postby Twistgrip » Thu Nov 15 2018, 11:59

That’s a good explanation of the questions posed Fatboy.

Below is an AAIB report I came across today which details history of the flight and also weather and the wind data is there also Flyhuey.
https://assets.publishing.service.gov.u ... G-VSKP.pdf
https://assets.publishing.service.gov.uk/media/5bebe118e5274a083e73dc27/S1-2018_G-VSKP.pdf
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Skeeter
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Re: 169 crash

Postby Skeeter » Thu Nov 15 2018, 18:02

Tail rotor authority on the 169 is excellent.
Max allowable wind for hover / sideways or rearward flight is 50kts in a sector 240° - 120°, then 35kts for further 30° and from 150° - 210 its 25kts.
workinman
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Re: 169 crash

Postby workinman » Fri Nov 16 2018, 04:23

In answer to all of the above regarding the profiles, they are published in the RFM, and are the only way therefore to guarantee performance profiles and obstacle clearance when carrying out Category A or PC 1 approaches and departures. If you are required to carry out those styles of approaches and departures then you are stuck utilising those as published by the manufacturer.
ozloadie
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Re: 169 crash

Postby ozloadie » Fri Nov 16 2018, 04:25

This might be of interest. Source: AIN

Emergency Tail Rotor AD Issued for AW169, AW189
by Mark Huber
NOVEMBER 8, 2018, 11:25 PM
EASA has issued an Emergency Airworthiness Directive (AD), effective November 9, in the wake of the fatal October 27 crash of a Leonardo AW169 in Leicester, UK, that killed all five aboard. The AD mandates the inspection of all AW169s and AW189s for correct installation of the tail rotor servo-actuator. The AD was extended to AW189s as the tail rotor flight control system on it is similar to the one on the AW169. The inspections are to take place within five flight hours or 24 hours of the effective date of the AD, whichever comes first.
If anomalies are detected then corrective action is to be taken per Leonardo Alert Service Bulletins (ASBs) 169-120 and 189-213; if none are detected then, before next flight, a paint mark is to be applied on the nut from the rod end to the hinge bracket element in accordance with applicable ASB instructions. The results of all inspections are to be reported to Leonardo within seven days.
In the accident that prompted the AD, a 2016 AW169, G-VSKP, S/N 69018, crashed shortly after it lifted off from the center field pitch of King Power Stadium in Leicester City, UK. Eyewitness reports said the helicopter struggled to gain altitude to clear the stadium and then spiraled down rapidly into an adjacent parking lot, where it was consumed by a post-crash fire. Further eyewitness accounts and photography show pieces of the tail rotor assembly being shed before the aircraft entered a spin. The accident remains under investigation by UK’s Air Accidents Investigation Branch (AAIB) and EASA stressed that the “root cause” of the accident remains to be identified and the “technical investigation is still ongoing.”

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flyhuey
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Re: 169 crash

Postby flyhuey » Fri Nov 16 2018, 12:23

Workinman:
Not sure if stuck using those profiles . . . From the PDFs and references I supplied seems there is no consensus among Pilots surveyed or a mandate by Aviation Regulators. Unless it appears as a Limitation, Warning or Caution, in an Aircraft Flight Manual or as an Aviation Regulation, then it is not mandatory. A Manufacturer Recommendation is not a mandate.

Ozloadie:
Thanks for that. Yep, I read that . . . But, in the references and points made above, this is less a discussion about possible mechanical failure . . . AND, if an Anti-Torque Rotor component failed, I am questioning the viability of a vertical takeoff to OGE, then backing up to a certain point before making a normal forward takeoff and climb.

Suppose there is a Loss of Tail Rotor Effectiveness for whatever reason, I am questioning if it isn't better to takeoff and achieve some forward speed to enable the Vertical Fin to help directional control. I am guessing above 30 knots.

A bedtime story:
I was flying an Army single engine Bell Huey, loaded with Special Forces and their gear and Full Fuel minus whatever time it took us to fly from the Air Base to a confined area on top of an 8,500 ft. mountaintop. I was Lead, thus heavier than those who would approach subsequently. Just prior to being committed to the Confined Area landing, I ran out of Left Pedal (Tail Rotor authority) and the nose began a slow turn right . . . I lowered the Collective slightly, trading height for airspeed and followed the right turn over the side of the mountain and down into the valley. I was able to successfully fly out of the situation, but I do not recall what speed the Vertical Fin became effective . . .

So, Ozloadie, that is where I am going with this discussion. If an aircraft is flying backward OGE and loses Tail Rotor authority for any reason, then there would be almost no chance to recover, except to autorotate, immediately to slow the rotation . . . and pull at the bottom, but it will likely be messy, anyway, if there is any rotation at touchdown . . . or if OGE and high enough, it might be possible to lower collective, nose over to build speed and follow the rotation with cyclic and build more speed if/when clear of obstacles . . . to get the Vertical Fin "flying".
Skeeter
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Re: 169 crash

Postby Skeeter » Fri Nov 16 2018, 22:08

flyhuey wrote:Workinman:
Not sure if stuck using those profiles . . . From the PDFs and references I supplied seems there is no consensus among Pilots surveyed or a mandate by Aviation Regulators. Unless it appears as a Limitation, Warning or Caution, in an Aircraft Flight Manual or as an Aviation Regulation, then it is not mandatory. A Manufacturer Recommendation is not a mandate.


EASA CAT.POL.H.100 Applicability
(a) Helicopters shall be operated in accordance with the applicable performance class requirements.
(b) Helicopters shall be operated in performance class 1:
(1) when operated to/from aerodromes or operating sites located in a congested hostile environment, except when operated to/from a public interest site (PIS) in accordance with CAT.POL.H.225; or
(2) when having an MOPSC of more than 19, except when operated to/from a helideck in performance class 2 under an approval in accordance with CAT.POL.H.305.
(c) Unless otherwise prescribed by (b), helicopters that have an MOPSC of 19 or less but more than nine shall be operated in performance class 1 or 2.
(d) Unless otherwise prescribed by (b), helicopters that have an MOPSC of nine or less shall be operated in performance class 1, 2 or 3.
....


At least in EASA land, you are sometimes required to fly a PC1 profile.
The requirement may be aswell mentioned in the AOC, coming from the council or the customer.

However, CAT means Commercial Air Transport and to my knowledge, this flight would have been governed by NCC = Non Commercial Complex.
There is nothing like this mentioned in NCC.

flyhuey wrote:Ozloadie:
Thanks for that. Yep, I read that . . . But, in the references and points made above, this is less a discussion about possible mechanical failure . . . AND, if an Anti-Torque Rotor component failed, I am questioning the viability of a vertical takeoff to OGE, then backing up to a certain point before making a normal forward takeoff and climb.

Suppose there is a Loss of Tail Rotor Effectiveness for whatever reason, I am questioning if it isn't better to takeoff and achieve some forward speed to enable the Vertical Fin to help directional control. I am guessing above 30 knots.


The profile is a continuous backup / climb with a roc of less than 300 fpm keeping the landing area in sight. No step included whatsoever.
Depending on the obstacle height it can go up to 400 ft.
In this case, the helicopter stopped initially at 320 ft which might be an indication that there are quite high obstacles in the departure path. Either the stadium itself or something beyond.

flyhuey wrote:So, Ozloadie, that is where I am going with this discussion. If an aircraft is flying backward OGE and loses Tail Rotor authority for any reason, then there would be almost no chance to recover, except to autorotate, immediately to slow the rotation . . . and pull at the bottom, but it will likely be messy, anyway, if there is any rotation at touchdown . . . or if OGE and high enough, it might be possible to lower collective, nose over to build speed and follow the rotation with cyclic and build more speed if/when clear of obstacles . . . to get the Vertical Fin "flying".


At least from my experience in the simulator, the 169 doesn't "fly" at any speed with a TR failure.
It was always a more or less controlled continues descend with only a little power applied to line us up with suitable landing site for the autorotation.

A helicopter is full of pieces which failure would be catastrophic.
Nevertheless, the (low) likelihood of an engine failure has been determined to be higher than a tail rotor failure etc.

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