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DHC Beaver down in Hawkesbury

Old 4th Jan 2018, 12:55
  #161 (permalink)  
 
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Originally Posted by 1a sound asleep View Post
Because its cheaper to rebuild than buy a new one (unavailable). People rebuild wrecks from the ID plate only basically hand rebuilding the airframe and often better than original

I am really thinking this is irrelevant to the investigation
There's an elderly LAME at YCWR who's slowly building a Beaver from scratch.
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Old 4th Jan 2018, 18:27
  #162 (permalink)  
 
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Desert Flower . . . . . if you knew the man, his 'circumstances', and what he has achieved in a long, long involvement at a professional level in aircraft maintenance, you would be a trifle less smart-arse. Methinks.
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Old 4th Jan 2018, 20:08
  #163 (permalink)  
 
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Originally Posted by Angle of Attack View Post
Connedrod , with all respects what did you just say?
The breaver in standard form is not fitted with a stall warning system. It also dose not have a pilot operating manual or handbook.

Robbies, air ag, superspread had the worlds largest operating fleet of these aircraft , approx 85.

Large superphosphate heaps of over 1500 ton (imperial)
A breaver on a good day strip etc will lift a ton and will do 100 ton a day.

Awt wings where fitted with a stall warning. Awt where a aftermarket wing shaped like a c185 of sorts.

What i am saying for the ill informed is a stall warning will not provide anything and is proven with the amount of flying hours that just thoose 3 companys record would show.

And as for the seats once again irrelevant. The floats show damage back approx 5 feet. The prop blades are pushed back and are around the engine.
The front screens would have pop out and provided zero resistance to the inflow of water. No seat would have provided any protection with the force of water going into the cabin.

One has to feel for all thoose involved in this accident. The ceo and owner interview was extremely moving and heart felt. To stop all operations shows what a quality operation this is. To the maintenance personal who also must be worried sick.
Having been placed in this position myself with a similar accident i feel for all thoose involved.
The familys of Vh hts who,s have had all thoose memeroies revisted one cannot say words in your pain.
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Old 4th Jan 2018, 20:30
  #164 (permalink)  
 
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Originally Posted by FAR CU View Post
Desert Flower . . . . . if you knew the man, his 'circumstances', and what he has achieved in a long, long involvement at a professional level in aircraft maintenance, you would be a trifle less smart-arse. Methinks.
My apologies. I probably DO know him - just not by his PPRuNe handle.

DF.
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Old 4th Jan 2018, 21:34
  #165 (permalink)  
 
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The 1st responders were true heroes if they entered the water fearing a fuel fire.

Based on Ppruners experiences, should the risk of post crash ignition of floating fuel be considered “low”
by first responders?

Yes consequences are severe but risk is low?
Mjb
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Old 4th Jan 2018, 23:22
  #166 (permalink)  
 
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Originally Posted by mickjoebill View Post
The 1st responders were true heroes if they entered the water fearing a fuel fire.

Based on Ppruners experiences, should the risk of post crash ignition of floating fuel be considered “low”
by first responders?

Yes consequences are severe but risk is low?
Mjb
The fire risk may have been low but the risk of cemical burns remain high.
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Old 5th Jan 2018, 00:01
  #167 (permalink)  
 
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It also dose not have a pilot operating manual or handbook
Well, it does in FAA land, produced/published by DH Canada, and is an FAA approved document. Got one. Not good enough for CASA are you implying? I doubt it.
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Old 5th Jan 2018, 00:07
  #168 (permalink)  
 
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Originally Posted by megan View Post
Well, it does in FAA land, produced/published by DH Canada, and is an FAA approved document. Got one. Not good enough for CASA are you implying? I doubt it.
Do your research a little.
Just wondering on what you think the prop speed was on impact
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Old 5th Jan 2018, 00:55
  #169 (permalink)  
 
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Originally Posted by john_tullamarine View Post
I would have thought that a very high value of longitudinal deceleration would have been against it. More damage to the fuselage would have been desirable.

Concur with those thoughts.

And of course the vintage of the seats and restraints (9G longitudinal).

I have no idea what standards applied to the original Beaver certification (and am not overly interested in searching them out) but, being of ancient vintage, it might even predate the 9G static restraint.

re the seats... they may be of a rated G but what are the floor tracks?



Depending on the seat certification, one would expect that the seats are matched to the more restrictive of the aeroplane certification requirements and the seating standards of the day. Certainly that was the process at Ansair (an Ansett subsidiary, now long defunct) when, for many years, I was the certification delegate for aircraft seat manufacture.

accident (turbine DC3) that stalled on takeoff in ground effect and slid across the snow to a halt. Everyone survived, still safely in their seats. Except they were neatly piled up in the front end of the fuselage...

Again, one would need to know the relevant standards for the particular aircraft. The original DC3s had 6g static seats.
BCAR dated 1947 with a technical letter which purported to be harmonisation with CAR3 CAR3.386 specifies 9G forward for NUA. Seats coming out of fuselage structure has always been a problem, but particularly so with the Beaver and hence AD/DHC-2/26. Civil Aviation Medical Institute in OKC is having a bit of a review of FAR2?.562, but the industry will not be happy if the requirements go up (lets face it any tightening of the rules is not going to happen)
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Old 5th Jan 2018, 02:56
  #170 (permalink)  
 
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Do your research a little
Well, I'm asking you, why doesn't it have a pilot operating manual or handbook?
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Old 5th Jan 2018, 04:09
  #171 (permalink)  
 
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Originally Posted by Connedrod View Post
The breaver in standard form is not fitted with a stall warning system. It also dose not have a pilot operating manual or handbook.
I don't think that comment with regards to the manual is correct.

A regulatory authority will not certify an aircraft type without a flight manual. The Australian (CASA) type acceptance certification for the DHC-2 (Number A129 Issue 2) is based on Canada's original certification (Aircraft Type Approval A-22). The De Havilland Aircraft of Canada Limited DHC-2 Beaver Flight Manual of 31 March 1956 is listed as the approved document in Canadian certification; you can source copies of the flight manual online.

Last edited by MickG0105; 5th Jan 2018 at 04:24. Reason: Correction
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Old 5th Jan 2018, 04:18
  #172 (permalink)  
 
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Connedrod, a quick google search comes up with a Beaver flight manual.

https://washingtonseaplanepilots.org...Beaver-POH.pdf

Why do you say there isn't one?
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Old 5th Jan 2018, 09:43
  #173 (permalink)  
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suffice to say the pax I met weren’t subjected to anything like 6 G and the seats pulled out of the floor.

The typical problem associated with seat separation with static design seats relates to seat and/or aircraft structure deformation which leads to the leg buttons being loaded asymmetrically, failing and away it goes. Hence the better situation with static seats bolted to structure in one way or another.

Some may recall that delightful ANR 40 chap, Rudy Paspa. One of his efforts involved designing and patenting (as I recall) an ellipsoid button which rotated on seat installation into the seat track so that the restraint capability was improved.

It was this deformation problem in mishaps which led to the requirement with newer dynamic seat certifications that the sled test required a preset misalignment of the seat to floor attachment to provide some comfort.

BCAR dated 1947 with a technical letter


Thank you, good sir .. saves me some trouble in researching the matter.
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Old 5th Jan 2018, 10:20
  #174 (permalink)  
 
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Connedrod said No Australian manual. I am not saying ther is a problem but the one you are quoting is US and Canadian. It is usual for the Certifying agency to either issue their own or Reference the manufacturers one.There are many aircraft ( like HS125) that have different speeds between the UK and the FAA manuals.
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Old 5th Jan 2018, 11:07
  #175 (permalink)  
 
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Originally Posted by GotTheTshirt View Post
Connedrod said No Australian manual.

No, he did not. He said

It also dose not have a pilot operating manual or handbook.
It does. De Havilland Aircraft of Canada Limited published the DHC-2 Beaver Flight Manual on 31 March 1956.
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Old 5th Jan 2018, 16:39
  #176 (permalink)  
 
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Mick
Sorry !! as this is an antipodean site and it was an Australian registered aircraft .........!!! I assumed he meant an Australian CAA one
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Old 5th Jan 2018, 23:55
  #177 (permalink)  
 
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Originally Posted by Connedrod View Post
The breaver in standard form is not fitted with a stall warning system. It also dose not have a pilot operating manual or handbook.

Robbies, air ag, superspread had the worlds largest operating fleet of these aircraft , approx 85.

Large superphosphate heaps of over 1500 ton (imperial)
A breaver on a good day strip etc will lift a ton and will do 100 ton a day.

Awt wings where fitted with a stall warning. Awt where a aftermarket wing shaped like a c185 of sorts.

What i am saying for the ill informed is a stall warning will not provide anything and is proven with the amount of flying hours that just thoose 3 companys record would show.

And as for the seats once again irrelevant. The floats show damage back approx 5 feet. The prop blades are pushed back and are around the engine.
The front screens would have pop out and provided zero resistance to the inflow of water. No seat would have provided any protection with the force of water going into the cabin.

One has to feel for all thoose involved in this accident. The ceo and owner interview was extremely moving and heart felt. To stop all operations shows what a quality operation this is. To the maintenance personal who also must be worried sick.
Having been placed in this position myself with a similar accident i feel for all thoose involved.
The familys of Vh hts who,s have had all thoose memeroies revisted one cannot say words in your pain.
I was originally going to post a sarcastic reply, but broadacre superphosphate operations have little relevance to float plane operations in and around lakes and ravines. - The previous accident (IDI 1996). Whether there was massive water inrush would be shown by the unzipping of the fuselage skins - difficult to see. Structurally float attachments at the front of the float are really strong (for loads from the plunge case). Hence there is a violent pitch (one way or the other) on impact. The fact that it stayed upright is significant. As for us "ill informed", who reckons the beaver would meet the flight requirements of FAR23 (let's say at amendment 45)?
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Old 6th Jan 2018, 11:37
  #178 (permalink)  
 
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who reckons the beaver would meet the flight requirements of FAR23 (let's say at amendment 45)?
Once certificated, an aircraft does not have to retrospectively satisfy any new certification standards that are promulgated. Therefore, the Beaver would only have to meet the standards required at the time of its initial certification. There are, therefore, many aircraft flying which do not meet current certification standards.

One aspect of stalling requirements for part 23 certification that needs to be taken into account is that stall tests are flown wings level and with 30 deg AoB in both directions, and all are flown with idle power and 75% max continuous power. Stalling characteristics at higher power settings and greater bank angles/normal accelerations are not tested and, therefore, some aircraft may demonstrate adverse stalling characteristics at high power and high g and still be certificated.

#78 provides a link to a Beaver Flight Manual in which, on page 36 of Section IV, it gives values for stall speeds at different bank angles/normal accelerations. There are two interesting points about this data. First, does it relate to aircraft with wheels, skis or floats? I would expect a difference between, say, wheels and floats due to the floats reducing overall directional and longitudinal static stability (resulting from surface area forward of the c.g). Secondly, [email protected]>1g = [email protected] x sq rt(load factor). From the Manual, [email protected] = 60 mph and [email protected] = 105 mph. Theoretically, [email protected] should be 84 mph. Can any Beaver operators explain this discrepancy? It is not uncommon for accelerated stall speeds to be lower than theoretical (usually due to Reynolds' number effects) but I have never before come across an aircraft where they are greater.

Please note that my comments above are not a comment on the accident but points of interest resulting from other posts on this thread.
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Old 6th Jan 2018, 13:08
  #179 (permalink)  
 
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Lomcevak
A national regulatory authority can apply any standards seen as reasonable and justifiable irrespective of the country of origin certification basis.
Compliance with an airworthiness certification standard does not automatically guarantee the product is truly fit to fly eg DH Comet.
Anyway, that is not my reading of the OP's comment re FAR Part 23.
It could be the Australian ATSB recommends an artificial stall warning be fitted.
FAR Part 23.203 requires accelerated stall tests at up to 5kts per second deceleration rate. Clearly at 75% power and 30 degrees of bank, light weight, considerable G will be applied for these test. These same test can result in almost aerobatic attitudes with extremely low airspeeds.
Also, 1 turn spin test are required of all (FAR23) single engine aircraft - by implication this gives test pilots further opportunity to assess stall characteristics.
I am not sure why changes in longitudinal and directional static stability would affect stall speeds. In any case, any stability deficiencies are normally addressed by aerodynamic add-ons and revised CG limits.
There are differences in the various Beaver manuals available on-line. The anomaly you noted is not present in all the manuals that I viewed. Similarly, at least one manual showed stall speeds for, land plane, ski plane, and float plane - there being no differences in speeds according to that manual.
Simple theory for stall speeds under various g loadings may not give you the expected results if you don't know the airspeed pressure error correction under G.

Last edited by zzuf; 6th Jan 2018 at 13:37.
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Old 6th Jan 2018, 14:01
  #180 (permalink)  
 
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zzuf,

I should have made myself clearer re certification. I was referring to initial certification by a regulatory authority. Obviously, there will often be no read across from one authority to another so an aircraft will have to satisfy the requirements at the time for issuing a type certificate.

I used the phrase 'accelerated stall' to mean a stall at greater than 1g (as per Def Stan 00-970 and Mil Specs). FAR23 and CS23 use the same phrase to mean a deceleration rate of 3-5 IAS per second - again, apologies for ambiguous phraseology. At 30 deg AoB and 75% MCP the pitch attitude will be high to achieve the deceleration but normal acceleration and IAS will be low. I have flown this test in a high powered piston aircraft under the old CAA Schedule 233 and been about 60 deg nose up with full rudder and almost full aileron, the ASI below its minimum value and still not reached an aerodynamic stall! However, normal acceleration was less that 1 due to the nose up attitude. Remember that it is pitch attitude that determines the deceleration rate, not normal acceleration.

Reduced directional stability may be mitigated by small extra fins but rarely will those compensate totally. The potential effect on stall speed is that stall characteristics may change due to the greater probability of having more sideslip present at the point of the stall, thereby resulting in a different stall speed. Rudder control strategy will have a major impact on this (eg. slipball central, zero yaw rate for wings level stalls, rudder free, rudder fixed from trim etc) because that is what will affect the sideslip at the stall. For a given cg. the longitudinal static stability may be affected by aerodynamic pitching moments from the floats, again potentially affecting pitch characteristics at the stall.

You are correct about ASI PECs affecting indicated stall speeds but it is actually AoA effects that are the cause rather than normal acceleration.

Please note that all of my points are generic and may not apply to the Beaver. Any thoughts on why different manuals have different stall speeds?

Rgds

L
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