Hercules questions

[John Farley]

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

[Father Jack Hackett]

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.....

[sycamore]

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.....

[John Farley]

Thank you very much chaps - 'twas as I imagined but very glad to have it confirmed

JF

[Tea White Zero]

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!):O

[bunta130]

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....:eek:

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......

[VinRouge]

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.

[fergineer]

Buntai you are correct the 15 degree micro switch in the flap quadrant does indeed give the high boost pressure.

[JammedStab]

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.....

Aircraft seems to handle a crosswind from either side about the same in my experience.

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).

[Kengineer-130]

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 :8, but poor old loadie has to manual the flaps & gear down as well :sad:, I imagine that could get interesting with a cargo bay full of meat bombs/ land rovers / webbers etc :ok:

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.

[Father Jack Hackett]

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......

[Old Fella]

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.

[JammedStab]

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......

Actually, I have not flown the aircraft in a while either.

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.

[JammedStab]

All those posting here must be young enough to never have had the pleasure of operating the C130A.

Booster Hydraulic System Engines 1 & 3, Utility System Engines 2 & 4.

Didn't know about the hydraulic setup for the 'A' model. Makes more sense. Why would Lockheed have changed it to left engines for Utility system and right engines for Booster. Just for saving complexity and therefore money?

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).

[Kengineer-130]

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!:ok:

[Old Fella]

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.

[JammedStab]

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.

Unfortunately, Canada lost a lot of Hercs.

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.

C-130 Damage from inflight prop seperation - YouTube

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

[ancientaviator62]

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.

[Old Fella]

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.

[US Herk]

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! :}

[JammedStab]

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.

You are correct, I had it backwards.

And yes, they did try to go around when they saw all the birds and then struck them. Certainly, suggesting that it may be better to accept the bird strikes and land through them.

As for having four fire bottles on A model Hercs....Nice, we only had two.

[Old Fella]

JammedStab, although we had four bottles on the A model, when discharged two bottles fired so we still only got one shot on each Normal and Reserve. The bottles, as I recall, were smaller than those on the H model and I can't recall about the E model, but I think it was the same as the H.

[Ken Scott]

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.

I think that many years of experience and usage have shown that that is indeed quite an unlikely occurrence. I've lost count of the number of engines I've had to shutdown but I've never (outside of the simulator) had to consider losing a second.

Still I've never quite understood the rationale behind the setup for the hydraulics or why the ground/air lever for the aux system isn't accessible in flight for emergency gear lowering. One of our crews a few years ago had to wind the gear down for a tech problem (I don't recall the specifics) then do the same on the next leg of the route after supposed rectification - and the gear didn't freefall in either case. I guess that the aux pump wouldn't be man enough to move all the landing gear at the same time but it could do it in sequence, or fit a bigger pump.

At least on the J model with its free turbines you can have the Number 2 windmilling after being shutdown providing utility pressure for gear & flap selection, but only provided the Number 1 goes first & if you haven't had to pull the fire handle on Number 2.

[JammedStab]

Still I've never quite understood the rationale behind the setup for the hydraulics or why the ground/air lever for the aux system isn't accessible in flight for emergency gear lowering.

One of our crews a few years ago had to wind the gear down for a tech problem (I don't recall the specifics) then do the same on the next leg of the route after supposed rectification - and the gear didn't freefall in either case. I guess that the aux pump wouldn't be man enough to move all the landing gear at the same time but it could do it in sequence, or fit a bigger pump.



Interconnects between hydraulic systems seem to be a ground only feature on many aircraft. The 727 was the same way. Although there did seem to be a 1 engine inoperative takeoff procedure where the CB for that interconnect on the 727 would be pulled on the ground(while the valve had been selected open by a switch) in order for it to stay open to be able to get the gear up in case of a second engine failure depending on the inoperative engines.

Won't work on the good old Herc though with the outside manual handle being the way to connect systems. Well there is the nosegear.

As for winding the gear down, that 600 turns. That must have been a good workout.

[Old Fella]

I tried to get re-chargable High Torque electric drills installed for use in manual gear or flap extension. Like lots of suggestions this one fell on "deaf ears". One of the reasons hydraulic systems are kept isolated from one another is because of the possible cross-contamination. A system flush takes a lot of time and consumes many gallons of hydraulic fluid.

[OmegaV6]

As for winding the gear down, that 600 turns. That must have been a good workout.

Bad enough if done with an empty airframe, reasonably tolerable if done with Army pax on board as you can "request" one of the fitter erks to do the winding .....

but with a full palletised load, or even worse, an ISO container ... an absolute pain as access to the winding position was "limited" to say the least ... :(

[JammedStab]

Bad enough if done with an empty airframe, reasonably tolerable if done with Army pax on board as you can "request" one of the fitter erks to do the winding .....

but with a full palletised load, or even worse, an ISO container ... an absolute pain as access to the winding position was "limited" to say the least ... :(

Then there is the idea of disconnecting the main gear to manually lower it when there is only a few inches of space between your solid, full length, one piece load that comes within inches of the sidewall.

[Chugalug2]

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.
I would say that far more likely was the likelihood of the whole aircraft being taken out by a single small arms round entering a fuel tank, for the want of any ballistic/explosive protection whatsoever (in the case of RAF Hercules at least). That was despite repeated pleas over decades from the workface that similar protection to USAF aircraft (ie ESF) be fitted. It was not until an aircraft was lost and 10 men killed that grudgingly such protection was provided. As you say, given that it is designed as a Tactical Transport, such protection should come as standard, though no doubt the MOD would have required its removal if that had been the case!

[Ken Scott]

As for winding the gear down, that 600 turns. That must have been a good workout.

Fortunately there was a student ALM on board who needed the exercise!

[Kengineer-130]

Chug has a point, much like sending "dumb" frames into known missile threat areas with only IRCM.... :mad:

[RMAF C130]

Critical engine.. of course eng no 1. Due to direction of propeller rotation ànd it can be explain on propeller theory... what in my mind is.. what the equation that can discribe of 5 deg toward life eng is required to maintain straight n level flight. The same angle of bank being used for every type of aircraft.. anybody can help me??

[VinRouge]

This paper will help RMAF:

http://www.cast-safety.org/pdf/5_asymmetric_flight.pdf

[gopher01]

As one who, on a east bound crossing of the pond was on a Herc with a precautionary engine shut down, for what reason escapes me now, observed the restart of the suspect engine as the oil leak on the inboard engine was considered the greater of the two evils. The shut down of two engines without any outside intereference i,e, enemy actio, birdstrikes was indeed possible if not probable. As having seen Harry ' butterfly' Burgoyne try to decimate Rhodesias' avian population on one sortie during the Commomwealth Monitoring Force operation, we counted 128 birdstrikes on the leading edges and prop spinners, we decided Albert could deal with them quite well. What the aerodynamics of the leading edges were like would be another matter and it was in fact the first aircraft sent home from Rhodesia. Memories of some astounding flying with the captain of the aircraft I operated with making his name in the Telegraph just recently.