Hercules questions
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Hercules questions
I have been asked by an academic:
Which is the critical engine and in the case of a critical engine out approach which way would you prefer any crosswind?
Not wishing to guess I thought I would ask those who know.
Ta
JF
Which is the critical engine and in the case of a critical engine out approach which way would you prefer any crosswind?
Not wishing to guess I thought I would ask those who know.
Ta
JF
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I haven't flown Albert for a few years, but I think I can recall the fundamentals so here goes....
The No. 1 (port outboard) is the critical engine. This is due to the thrust line of the engines being offset slightly to the starboard, due to some sort of progression jiggery pokery (that Aero Eng degree didn't do me much good) resulting from the clockwise (viewed from the aft) rotation of the props. Therefore the live No. 4 (starboard outboard) engine would produce more of a yawing moment than if the situation were reversed.
In terms of the approach, I believe it was better to have a crosswind from the right, as during asymmetric handling with the critical engine failed, one would have both right rudder trim and up to 5 degrees right-wing-down ("5 to the live") aileron trim to balance the asymmetry. However, a crosswind from the left (failed side) favoured handling on the landing roll as the weather-cocking effect would ameliorate the asymmetric drag effect of the No.4 being in flight-idle, then ground idle while the inboards are in reverse and the failed prop is feathered/stopped.
Again, my recall is a bit rusty, but I believe it was considered preferable to take a crosswind from the left as the after-landing effects were trickier to deal with than the effects of crosswind on approach.
Standing by to be shot down by my former colleagues.....
The No. 1 (port outboard) is the critical engine. This is due to the thrust line of the engines being offset slightly to the starboard, due to some sort of progression jiggery pokery (that Aero Eng degree didn't do me much good) resulting from the clockwise (viewed from the aft) rotation of the props. Therefore the live No. 4 (starboard outboard) engine would produce more of a yawing moment than if the situation were reversed.
In terms of the approach, I believe it was better to have a crosswind from the right, as during asymmetric handling with the critical engine failed, one would have both right rudder trim and up to 5 degrees right-wing-down ("5 to the live") aileron trim to balance the asymmetry. However, a crosswind from the left (failed side) favoured handling on the landing roll as the weather-cocking effect would ameliorate the asymmetric drag effect of the No.4 being in flight-idle, then ground idle while the inboards are in reverse and the failed prop is feathered/stopped.
Again, my recall is a bit rusty, but I believe it was considered preferable to take a crosswind from the left as the after-landing effects were trickier to deal with than the effects of crosswind on approach.
Standing by to be shot down by my former colleagues.....
J F, No.1 ,left outboard,as the props rotate C-W(from rear).Also need >20 deg. flaps for full rudder boost.T/O usually at 50 flap anyway.
Preferably X- wind from right,and either 50 flap landing if it`s turbulent,or 100 if commited and Captain`s wind down the strip. Don`t know about J-model but probably same.
Inboards only reverse on landing,and don`t let into -wind wing rise.
If both out on left,50 flap for landing,and gentle reverse on no.3/4.
`Fun` if it`s wet/contaminated.....
Preferably X- wind from right,and either 50 flap landing if it`s turbulent,or 100 if commited and Captain`s wind down the strip. Don`t know about J-model but probably same.
Inboards only reverse on landing,and don`t let into -wind wing rise.
If both out on left,50 flap for landing,and gentle reverse on no.3/4.
`Fun` if it`s wet/contaminated.....
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Not so much of a factor with the C130J fitted with FADECs as the Auto Thrust Control System (ATCS) retards the power on the opposing outboard engine and thus not making it so critical. (IIRC from those ground school notes!)
It is indeed as Father Hackett remembers it. #1 is critical in Vmca terms, and crosswind would be better from the live engine side for the overshoot case, as you certainly did not want to have bank towards the dead engine if another failed on the same side with power levers going forward....
For the landing, you would prefer the crosswind from the dead engine side....the mantra 'swing and dip towards the live' was oft repeated during the brief. The swing would be partially offset by the wind from the dead engine side (acting on the rudder and weather-cocking you into wind) as you crossed the gate from flight to ground range....unfortunately, the dip would be exacerbated.
Once saw a (rather overconfident) TP nearly depart the runway showing a fellow TP what it was like when you took the wind from the wrong side...practise asymmetric.
Rust hopefully fallen away......along with my hair.......
Nit-picking...wasn't the high rudder boost as you went through 15%...only setting 20% to be on the safe side.....?
7 knots....now what was the question?
Only edible part?
Highest power draw?
Ooooh the ground cat joys......
For the landing, you would prefer the crosswind from the dead engine side....the mantra 'swing and dip towards the live' was oft repeated during the brief. The swing would be partially offset by the wind from the dead engine side (acting on the rudder and weather-cocking you into wind) as you crossed the gate from flight to ground range....unfortunately, the dip would be exacerbated.
Once saw a (rather overconfident) TP nearly depart the runway showing a fellow TP what it was like when you took the wind from the wrong side...practise asymmetric.
Rust hopefully fallen away......along with my hair.......
Nit-picking...wasn't the high rudder boost as you went through 15%...only setting 20% to be on the safe side.....?
7 knots....now what was the question?
Only edible part?
Highest power draw?
Ooooh the ground cat joys......
Last edited by bunta130; 21st Nov 2011 at 20:16.
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Unless you got airbourne on MOS, below NOS Vmca, which in some cases for the J, the inboard could become the critical engine? could be wrong on this.
I remember retarding inboard throttles back from 4700 hp iin the sim on MOS takeoffs with an outboard failure, to maintain roll/lateral control. Reason being, ATCS reduces thrust on the outboard and yaw on the inboard thus could exceeded the outboard. Could get fruity at heavier weights hot n high.
I remember retarding inboard throttles back from 4700 hp iin the sim on MOS takeoffs with an outboard failure, to maintain roll/lateral control. Reason being, ATCS reduces thrust on the outboard and yaw on the inboard thus could exceeded the outboard. Could get fruity at heavier weights hot n high.
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I haven't flown Albert for a few years, but I think I can recall the fundamentals so here goes....
The No. 1 (port outboard) is the critical engine. This is due to the thrust line of the engines being offset slightly to the starboard, due to some sort of progression jiggery pokery (that Aero Eng degree didn't do me much good) resulting from the clockwise (viewed from the aft) rotation of the props. Therefore the live No. 4 (starboard outboard) engine would produce more of a yawing moment than if the situation were reversed.
In terms of the approach, I believe it was better to have a crosswind from the right, as during asymmetric handling with the critical engine failed, one would have both right rudder trim and up to 5 degrees right-wing-down ("5 to the live") aileron trim to balance the asymmetry. However, a crosswind from the left (failed side) favoured handling on the landing roll as the weather-cocking effect would ameliorate the asymmetric drag effect of the No.4 being in flight-idle, then ground idle while the inboards are in reverse and the failed prop is feathered/stopped.
Again, my recall is a bit rusty, but I believe it was considered preferable to take a crosswind from the left as the after-landing effects were trickier to deal with than the effects of crosswind on approach.
Standing by to be shot down by my former colleagues.....
The No. 1 (port outboard) is the critical engine. This is due to the thrust line of the engines being offset slightly to the starboard, due to some sort of progression jiggery pokery (that Aero Eng degree didn't do me much good) resulting from the clockwise (viewed from the aft) rotation of the props. Therefore the live No. 4 (starboard outboard) engine would produce more of a yawing moment than if the situation were reversed.
In terms of the approach, I believe it was better to have a crosswind from the right, as during asymmetric handling with the critical engine failed, one would have both right rudder trim and up to 5 degrees right-wing-down ("5 to the live") aileron trim to balance the asymmetry. However, a crosswind from the left (failed side) favoured handling on the landing roll as the weather-cocking effect would ameliorate the asymmetric drag effect of the No.4 being in flight-idle, then ground idle while the inboards are in reverse and the failed prop is feathered/stopped.
Again, my recall is a bit rusty, but I believe it was considered preferable to take a crosswind from the left as the after-landing effects were trickier to deal with than the effects of crosswind on approach.
Standing by to be shot down by my former colleagues.....
You want a significant crosswind from the dead engine side for the approach. For example, with a strong right crosswind on landing, you need a significant amount of left rudder on the landing roll. If #4 engine is feathered(#1 is the critical engine), after touchdown when the props are brought into beta, the large amount of asymmetric drag from the #1 prop will swing to the left meaning that less rudder input is needed and helping you, so you can ease off rudder input.
Don't forget to quickly put in a bunch of counteracting aileron as the aircraft will roll as well due to a lot more lift on the feathered engine side as the airflow is not disturbed behind the feathered prop(and the crosswind tending to lift the upwind wing combined with the narrow gear track). If you land in the opposite direction, you have the crosswind, asymmetric drag and a turning moment from the roll(if allowed to develop) pulling you to the side of the runway.
It is correct that the high boost pressure is from a microswitch in the flap lever at 15°. That is why, you select the flap lever to 20° even if you have no hydraulics to operate the flaps(or flaps not operating for another reason) such as engines 1 and 2 inoperative. Or a broken flap cable detected(civilian Herc).
Last edited by JammedStab; 19th Jan 2012 at 20:25.
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The other thing to consider is that the Hydraulics for the gear & flaps are only powered from the utility system, that is supplied by only #1 & #2 donkeys, so should you suffer a double engine failure on the port side, not ony do the crew have to deal with all the piloty stuff 
, but poor old loadie has to manual the flaps & gear down as well 
, I imagine that could get interesting with a cargo bay full of meat bombs/ land rovers / webbers etc 
It told it's own story that we (engineers) were never allowed to fly if the crew were practicing double asymetric, hairy even in a controlled training enviroment by all accounts.
, but poor old loadie has to manual the flaps & gear down as well , I imagine that could get interesting with a cargo bay full of meat bombs/ land rovers / webbers etc It told it's own story that we (engineers) were never allowed to fly if the crew were practicing double asymetric, hairy even in a controlled training enviroment by all accounts.
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JammedStab,
While you seem to have an overall grasp of the situation, you seem to be 180 out with the roll effect. A live outboard engine will produce more of a rolling moment than a feathered prop as the greater acceleration of airflow over the airfoil due to the latent thrust of the live prop will result in greater lift over that portion of wingspan than the free airflow over the portion of wingspan downstream of a feathered prop.
In the latter stages of an assymetric landing in Albert, you need a substantial amount of aileron towards the live side to counteract this effect, the outboard engine having to remain in flight idle (producing significant residual thrust) until directional control is sufficiently assured to bring said prop into ground idle (producing drag commensurate with forward speed).
Again, a health warning comes with the above as I've not flown The Queen Of The Sky for a while, but I think I'm thereabouts......
While you seem to have an overall grasp of the situation, you seem to be 180 out with the roll effect. A live outboard engine will produce more of a rolling moment than a feathered prop as the greater acceleration of airflow over the airfoil due to the latent thrust of the live prop will result in greater lift over that portion of wingspan than the free airflow over the portion of wingspan downstream of a feathered prop.
In the latter stages of an assymetric landing in Albert, you need a substantial amount of aileron towards the live side to counteract this effect, the outboard engine having to remain in flight idle (producing significant residual thrust) until directional control is sufficiently assured to bring said prop into ground idle (producing drag commensurate with forward speed).
Again, a health warning comes with the above as I've not flown The Queen Of The Sky for a while, but I think I'm thereabouts......
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Reduced Rudder Pressure.
All those posting here must be young enough to never have had the pleasure of operating the C130A. Booster and Utility Systems operate at 31-3200 PSI, reduced to 1500 PSI Rudder Boost regardless of flap position. Booster Hydraulic System Engines 1 & 3, Utility System Engines 2 & 4. No electric Aux system, just the Air Turbine Motor driving the Emergency Hydraulic Pump. Also, AC Generator on Engines 2 & 3 only and ATM. DC Generators on all engines. 15' diameter Aero Products 3 blade props. Best of all, MTOW 124200 lbs. Hence, "A for GO - E for SHOW" back in the old days.
Last edited by Old Fella; 20th Jan 2012 at 04:22.
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JammedStab,
While you seem to have an overall grasp of the situation, you seem to be 180 out with the roll effect. A live outboard engine will produce more of a rolling moment than a feathered prop as the greater acceleration of airflow over the airfoil due to the latent thrust of the live prop will result in greater lift over that portion of wingspan than the free airflow over the portion of wingspan downstream of a feathered prop.
In the latter stages of an assymetric landing in Albert, you need a substantial amount of aileron towards the live side to counteract this effect, the outboard engine having to remain in flight idle (producing significant residual thrust) until directional control is sufficiently assured to bring said prop into ground idle (producing drag commensurate with forward speed).
Again, a health warning comes with the above as I've not flown The Queen Of The Sky for a while, but I think I'm thereabouts......
While you seem to have an overall grasp of the situation, you seem to be 180 out with the roll effect. A live outboard engine will produce more of a rolling moment than a feathered prop as the greater acceleration of airflow over the airfoil due to the latent thrust of the live prop will result in greater lift over that portion of wingspan than the free airflow over the portion of wingspan downstream of a feathered prop.
In the latter stages of an assymetric landing in Albert, you need a substantial amount of aileron towards the live side to counteract this effect, the outboard engine having to remain in flight idle (producing significant residual thrust) until directional control is sufficiently assured to bring said prop into ground idle (producing drag commensurate with forward speed).
Again, a health warning comes with the above as I've not flown The Queen Of The Sky for a while, but I think I'm thereabouts......
However, you mention that the outboard engine(the one still operating) remains in flight idle and therefore accelerates more air over its wing than the feathered engines wing.
Our procedure when after touchdown(nosewheel on the ground) with one engine inoperative was not to leave any engines in flight idle. All three operating engines were brought up onto the 'ramp' into ground idle(civilian aircraft-not sure if military ones had this position). After all operating engines were in ground idle, the symmetrical engines went into reverse.
When in ground idle is selected, the propellers go to a nearly flat pitch and block the airflow over the wing, reducing the lift on the wing during the rollout while the wing area behind the feathered prop provides much more lift and therefore roll toward the live engine side. This is combined with the increase in drag from the live engine side due to the "flat plate' drag of both props in ground idle.
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I always thought that it was a huge weakness of the aircraft to lose flap operation, gear operation and normal brakes with two engines out on the same side(left side).
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I never understood why there was not a simple isolation valve between the Utility & booster or Utility & aux ( ignoring the ground use only change-over lever) to allow a second system to operate the vital services of gear/flaps?
I suppose in all likelyhood, a double failure on one wing was such a rare event that it was not deemed a requirement? Still felt safer flying on Albert than almost any other aircraft!
I suppose in all likelyhood, a double failure on one wing was such a rare event that it was not deemed a requirement? Still felt safer flying on Albert than almost any other aircraft!
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Utility / Booster Hydraulic Configuration.
It is difficult to understand why the Hydraulic Systems configuration was changed from that on the C130A to the later configuration in relation to the Utility and Booster Systems other than for economic reasons. The Emergency Hydraulic System, powered by an ATM driven pump, on the A model was replaced by the Aux System in later variants. I guess in the scheme of things the chances of suffering two engines out on the same side are pretty slim. Never happened to me in my ten years on the C130, or on any other type for that matter. As for being able to divert booster system pressure to the gear and flaps I suspect that it is probably considered more important to maintain the integrity of the Booster System for its primary purpose, i.e. Flight Control Surface boost. The Aux System (Emergency System on the A) can be used to lower the NLG with the MLG and Flap having to be maunually extended. As Kengineer-130 said the Hercules is a very safe and, generally, forgiving aircraft. Over fifty years of service in the RAAF and never a hull lost.
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I guess in the scheme of things the chances of suffering two engines out on the same side are pretty slim. Never happened to me in my ten years on the C130, or on any other type for that matter.
As for being able to divert booster system pressure to the gear and flaps I suspect that it is probably considered more important to maintain the integrity of the Booster System for its primary purpose, i.e. Flight Control Surface boost.
As for being able to divert booster system pressure to the gear and flaps I suspect that it is probably considered more important to maintain the integrity of the Booster System for its primary purpose, i.e. Flight Control Surface boost.
When you consider that this is an aircraft designed for combat operations, one should think that it is quite likely that two engines on a side could be taken out and design better redundancy. When one looks at all the engine shutdowns due to valve housing problems and other reasons, it is actually quite common. Of my 11 shutdowns in 2,000 hours, 3 were not precautionary. Two were prop malfunctions. One was a mysterious flameout. Many others I know have had many more shutdowns.
A Dutch Herc had multiple engine failures due to birdstrike(It crashed due to VMC reasons), several Hercs seem to have thrown prop blades resulting in multiple engine failures.
The A model hydraulic systemsounds like it might have been a better design in some ways. I can see the reason now for keeping the Booster system isolated. While our sim may not have been fully representative of the actual flying characteristics of the aircraft(and the sims themselves seem to vary), I could never land one with a loss of flight control hydraulic pressure.
At the bottom of this page you can see that losing a prop may not be good for the hydraulics. Pretty close to the access panels.
http://www.f-16.net/gallery_item210678_page5.html
Jammed Stab,
which Dutch Herc crash are you referring to ? I remember a Belgian Herc crash at Eindhoven on 15 July 1996. (CH 06) . A great number of those on board died due to wrong decisions by the Eindhoven authorities in the immediate aftermath of the crash.
which Dutch Herc crash are you referring to ? I remember a Belgian Herc crash at Eindhoven on 15 July 1996. (CH 06) . A great number of those on board died due to wrong decisions by the Eindhoven authorities in the immediate aftermath of the crash.
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Engine Shutdowns C130
I am unsure of how many times I was part of the crew on flights on which we had to shut down an engine in flight on the C130. The C130A had only two engine driven AC Generators (Engines 2 & 3) and an ATM AC Generator plus a DC Generator on each engine. A number of shutdowns were due to an engine driven AC Generator failure, there being no drive disconnect system it was necessary to shut down the engine. Also, the oil scavenge system for the engine was modified to incorporate a duplex scavenge pump fitted on the accessory case. This mod led to a number of shutdowns due loss of oil due to seal failure. Every F/E carried at least one set of replacement seals. If during the after-flight check it was noted that oil was visible on the oil cooler flap actuator it was almost a sure bet the scavenge pump was the culprit. Prop failures were not a common problem, certainly not for blade shedding. Cannot recall a gearbox failure or separation on a RAAF C130A. A relatively common cause for engine shut-down on the A was a Nacelle Overheat, usually because the bleed air line to the inlet anti-ice failed. The RAAF A models also had optical fire detectors which could give a false fire warning on occasion. Though not a written action, a turn off heading could result in the warning extinguishing. Given that only four Fire bottles were available to service the four engines and the GTC, with two bottles fired each actuation it was really important to clearly identify and confirm a Fire Warning and "hasten slowly" before firing off the extinguisher. Enough of this anyway, totally off the original topic.
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Originally Posted by Jammedstab
A Dutch Herc had multiple engine failures due to birdstrike(It crashed due to VMC reasons), several Hercs seem to have thrown prop blades resulting in multiple engine failures.
It's been a long time since I read the accident report - didn't they suffer the birdstrikes on short finals and then attempt a go-around rather than land straight ahead?
My details are fuzzy as I'm also remembering it being a Belgian Herk carrying the Dutch band?? Or...
Damn those penguins!
