DHC Beaver down in Hawkesbury
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.
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.
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
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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Some pics of the float damage on Kathryns report site
http://www.kathrynsreport.com/2018/0...er-vh-noo.html
http://www.kathrynsreport.com/2018/0...er-vh-noo.html
Certification is really no more than a theoretical benchmark that we believe indicates than an aircraft will be safe and durable.
Unlike road vehicle certification which changes regularly to incorporate the lessons of real world experience, aircraft certification changes very rarely. So not only is it a theoretical benchmark, it’s an outdated theoretical benchmark.
The other approach is real world experience.
I would argue that the beaver more than most others has demonstrated that it passes the real world tests with margin to spare.
Unlike road vehicle certification which changes regularly to incorporate the lessons of real world experience, aircraft certification changes very rarely. So not only is it a theoretical benchmark, it’s an outdated theoretical benchmark.
The other approach is real world experience.
I would argue that the beaver more than most others has demonstrated that it passes the real world tests with margin to spare.
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
From the FAA TCDS.
Certification - CAR 10 in conformity with data forming the basis for DOT Aircraft Type Approval No. A-22 based on British Civil Airworthiness Requirements as amended to June 1, 1947, Normal Category, and Information Circular T/4/48 dated March 3, 1948. (This certification equivalent to CAR 3 dated November 13, 1945). FAA Airplane Type Certificate No. A-806 amended to May 6, 1953 was issued. Date of application for Type Certificate March 21, 1947 (to the DOT).
Equipment - The basic required equipment as prescribed in the applicable airworthiness regulations (see Certification Basis) must be installed in the aircraft for certification.
In addition, the following items of equipment must be in each aircraft at all times:
1. Canadian approved de Havilland DHC-2 Mk. I Flight Manual dated March 31, 1956.
2. Current de Havilland Beaver Weight and Balance Report, including list of Equipment in Certificated Weight Empty. (Items listed as required equipment must not be removed unless replaced by approved equipment items).
Equipment - The basic required equipment as prescribed in the applicable airworthiness regulations (see Certification Basis) must be installed in the aircraft for certification.
In addition, the following items of equipment must be in each aircraft at all times:
1. Canadian approved de Havilland DHC-2 Mk. I Flight Manual dated March 31, 1956.
2. Current de Havilland Beaver Weight and Balance Report, including list of Equipment in Certificated Weight Empty. (Items listed as required equipment must not be removed unless replaced by approved equipment items).
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.
.
.
Certification is really no more than a theoretical benchmark that we believe indicates than an aircraft will be safe and durable.
Unlike road vehicle certification which changes regularly to incorporate the lessons of real world experience, aircraft certification changes very rarely. So not only is it a theoretical benchmark, it’s an outdated theoretical benchmark.
The other approach is real world experience.
I would argue that the beaver more than most others has demonstrated that it passes the real world tests with margin to spare.
Unlike road vehicle certification which changes regularly to incorporate the lessons of real world experience, aircraft certification changes very rarely. So not only is it a theoretical benchmark, it’s an outdated theoretical benchmark.
The other approach is real world experience.
I would argue that the beaver more than most others has demonstrated that it passes the real world tests with margin to spare.
O
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.
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.
zzuf,
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.
L
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.
L
I had intended to leave the response as a PM, changed my mind due to other responses.
A requirement of FAR 23.203 is deceleration at 3 to 5 kts per second, "with steadily increasing normal acceleration". It seems that you have misinterpreted the FAR and that the tests you have done are not correct.
I typically tried for a stall at about 2g, generally it requires a bit of a work up to hit 2g (with g steadily increasing), 3 - 5 kts per second deceleration, 30 degrees of bank and stall simultaneously.
But, as you mentioned, there will be plenty of low g, low speed, high pitch attitude experiences as you develop a test procedure for a particular aircraft.
Don't forget these are test points to be demonstrated for certification, looks simple, but the workup may be time consuming and involve some exacting aircraft control. Of course after you hit the test point you need to accurately record the aircraft behaviour.
If you have ever flown tests to determine lift and thrust boundaries you will know that your last sentence (above) won't survive much scrutiny.
Cheers
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[QUOTE=megan;10012899]The flight manual says there is no difference in stall speed between wheels, skis or floats (Section IV, page 40).
From the FAA TCDS.
Hard to see our regulatory allowing operations without a flight manual when the FAA calls for its mandatory carriage. Bless me, Connedrod wrong,
Like i have stated. The dhc -2 was cerified in australia with out a stall warning and a fight manual, period. We are not under faa rules in case you didnt know. Abd btw i have worked on IDI as an ag machine. I am also lead to believe i was also involved on the transition to floats. I also have been involved in many rebuilds of dhc-2 beavers. So how many have you worked on or flown. Also family members that have over 160 hours flying time in idi.
Like i have previously stateed the aircraft in ag use had a 1 page statement that was on the fwd side of the hopper and thats it .
Prehaps you should learn some histroy before you say im wrong when in fact your the one thats incorrect and not the first time.
From the FAA TCDS.
Hard to see our regulatory allowing operations without a flight manual when the FAA calls for its mandatory carriage. Bless me, Connedrod wrong,
Like i have stated. The dhc -2 was cerified in australia with out a stall warning and a fight manual, period. We are not under faa rules in case you didnt know. Abd btw i have worked on IDI as an ag machine. I am also lead to believe i was also involved on the transition to floats. I also have been involved in many rebuilds of dhc-2 beavers. So how many have you worked on or flown. Also family members that have over 160 hours flying time in idi.
Like i have previously stateed the aircraft in ag use had a 1 page statement that was on the fwd side of the hopper and thats it .
Prehaps you should learn some histroy before you say im wrong when in fact your the one thats incorrect and not the first time.
zzuf,
I agree with what you have said and with respect to your reference to my last sentence:
I fear that in trying to be brief I have been ambiguous.
The instantaneous deceleration rate is a function of pitch attitude (which determines the longitudinal axis component of weight) but to keep longitudinal deceleration constant the pitch attitude must be increased at an increasing rate which, de facto, requires increasing normal acceleration. In practice, each pilot will develop a technique and scan pattern to achieve what is required to fly the test as it is required for certification. I use pitch attitude and decel rate and the required g increase then occurs.
megan,
Thanks for the steer to the stall data in Section IV.
Rgds
L
I agree with what you have said and with respect to your reference to my last sentence:
Remember that it is pitch attitude that determines the deceleration rate, not normal acceleration.
The instantaneous deceleration rate is a function of pitch attitude (which determines the longitudinal axis component of weight) but to keep longitudinal deceleration constant the pitch attitude must be increased at an increasing rate which, de facto, requires increasing normal acceleration. In practice, each pilot will develop a technique and scan pattern to achieve what is required to fly the test as it is required for certification. I use pitch attitude and decel rate and the required g increase then occurs.
megan,
Thanks for the steer to the stall data in Section IV.
Rgds
L
Last edited by LOMCEVAK; 7th Jan 2018 at 17:28.
Prehaps you should learn some histroy before you say im wrong when in fact your the one thats incorrect and not the first time
You'll remember you said originally,
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 have not flown FW on floats, just helicopters. I also do not know that area, but is wild bird life a problem given the vast area of water?
There may now be no evidence of a bird strike, or the pilot may have taken reflexive control input leading to a stall, if a large bird suddenly appeared right in front of him.
RIP all the victims.
There may now be no evidence of a bird strike, or the pilot may have taken reflexive control input leading to a stall, if a large bird suddenly appeared right in front of him.
RIP all the victims.
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id like to ask the guys here, as its been a while since i did air law.
Would this pilot have required a biennial review in this exact type of aircraft (a DHC2 float) or could he satisfy that requirement in the Caravan float ( single engine floatplane)
Would this pilot have required a biennial review in this exact type of aircraft (a DHC2 float) or could he satisfy that requirement in the Caravan float ( single engine floatplane)
Funny you should say that, OF. I made a post in this thread after my most recent flight, noting that I had 3 near misses - two with big birds and one with a flock of big birds. I also noted that I had watched a year of Senate Committee inquiries in which the danger caused by drones was causing great consternation.
For some reason it was deleted by the moderators.
----------------------------------------
It was deleted due to a reference to another post (also deleted) and your first line comment. I'm surprised you suggest you are
The acceptable part of your post was:
Tail Wheel
For some reason it was deleted by the moderators.
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It was deleted due to a reference to another post (also deleted) and your first line comment. I'm surprised you suggest you are
The acceptable part of your post was:
Just got back from a two day trip during which I had 3 near-misses with large birds and 1 near-miss with a big flock of large birds. Just sat through a year of Senate Committee hearings during which the extreme danger posed by drones was the biggest air safety risk of the century.
But I guess there are no birds or drones at low level around Cowan Creek, or that if there are, us super-pilots would be able to “keep focus on power and pitch”.
But I guess there are no birds or drones at low level around Cowan Creek, or that if there are, us super-pilots would be able to “keep focus on power and pitch”.
Carries CASA stamp of approval!
Interesting, is that a requirement still? I have seen a few of them around, but most were thrown in the bin.
Interesting, is that a requirement still? I have seen a few of them around, but most were thrown in the bin.
https://www.casa.gov.au/file/184221/...token=bQ9iGp1U
The original Canadian Beaver type certificate A-22, on which basis Australia accepted the aircraft, not from the FAA certification. Note the requirement to carry a flight manual in the certificate, must be carried at all times.
Connedrod, you're snookered.
http://wwwapps.tc.gc.ca/saf-sec-sur/...M=&id_num=1141
Last edited by megan; 8th Jan 2018 at 05:47.
Aircraft, other than those mentioned under paragraph 2.4.3 or Appendix A, are all required to have an AFM.
Here is para 2.4.3 for the snooker table!
The following aircraft may not be required to have an AFM:
a. aircraft up to a MTOW of2,722 kg (6,000 lb) manufactured and flown prior to 1 March 1979
b. historic and ex-military aircraft
c. amateur-built aircraft
d. experimental aircraft
e. hang gliders operated under Civil Aviation Order (CAO) 95.8
f. ultralight aircraft operated under CAO 95.10 and CAO 95.55
g. gyroplanes operated under CAO 95.12 and CAO 95.12.1
h. weight shift controlled aeroplanes and powered parachutes operated under CAO 95.32.
Here is para 2.4.3 for the snooker table!
The following aircraft may not be required to have an AFM:
a. aircraft up to a MTOW of2,722 kg (6,000 lb) manufactured and flown prior to 1 March 1979
b. historic and ex-military aircraft
c. amateur-built aircraft
d. experimental aircraft
e. hang gliders operated under Civil Aviation Order (CAO) 95.8
f. ultralight aircraft operated under CAO 95.10 and CAO 95.55
g. gyroplanes operated under CAO 95.12 and CAO 95.12.1
h. weight shift controlled aeroplanes and powered parachutes operated under CAO 95.32.