Re: b-17 left teterboro on 3 engines last night?
Thu Jun 21, 2012 10:07 am
Earlier in my airline carreer I remember references to 3-engined ferry flights in the Ops manual... who could do it, what circumstances, technique, etc. Airliners and bombers have a huge reserve of power if they operate with no payload and min fuel.
Nowadays we don't do it. There are few 4-engined aircraft left of course, but even so, the negative publicity that an accident would generate would be all out of proportion to the savings involved in getting the aircraft home.
Dave
Nowadays we don't do it. There are few 4-engined aircraft left of course, but even so, the negative publicity that an accident would generate would be all out of proportion to the savings involved in getting the aircraft home.
Dave
Re: b-17 left teterboro on 3 engines last night?
Thu Jun 21, 2012 10:11 am
bdk wrote:This would be a good Larry Krause question.
Nah, you got to feather two more engines until he gets interested!
Re: b-17 left teterboro on 3 engines last night?
Thu Jun 21, 2012 11:45 pm
True enough!
Re: b-17 left teterboro on 3 engines last night?
Fri Jun 22, 2012 2:12 am
Wildchild wrote:Well with the price of gas it would make since to stop an engine from eating gas. Remember my friends, $$$
You have no idea.
k5dh wrote:Perhaps the Navy fliers among us can answer this question: Is it, or was it, common practice among P-3 crews to shut down two engines once established on patrol in order to conserve fuel? I know I've heard that somewhere, but you know how rumors are.
It certainly used to be a show item of RAAF Lockheed Orions to do a couple of passes on three (only a couple of years ago now) and IIRC that was based on a patrol practice, if I'm not misremembering according to the commentary. Notably this weekend's RCAF Lockheed Aurora did not do such a thing, and my Canadian companions said they didn't think it happened.
Regards,
Re: b-17 left teterboro on 3 engines last night?
Fri Jun 22, 2012 5:19 am
k5dh wrote:Perhaps the Navy fliers among us can answer this question: Is it, or was it, common practice among P-3 crews to shut down two engines once established on patrol in order to conserve fuel? I know I've heard that somewhere, but you know how rumors are.
Yep, Brad has definitely told me they did this quite regularly when he was flying the Orion in the 90s.
Re: b-17 left teterboro on 3 engines last night?
Fri Jun 22, 2012 6:01 am
I remember hearing about DT's Liberator leaving NJ to go to OQU back in the 90s with one that was on its way out.
They shut it down after takeoff, and then got a call from ATC asking if everything was OK.
A passing airliner saw them with one feathered, and called it in.
There is always someone watching.
The #1 cylinder on that engine had come off.
They shut it down after takeoff, and then got a call from ATC asking if everything was OK.
A passing airliner saw them with one feathered, and called it in.
There is always someone watching.
The #1 cylinder on that engine had come off.
Re: b-17 left teterboro on 3 engines last night?
Fri Jun 22, 2012 6:04 am
I think everyone agrees that it can be done. I think a better question is SHOULD it be done. Should you DEPART knowing you only have three engines. My vote is no. I also am interested to know if it is even legal.
Re: b-17 left teterboro on 3 engines last night?
Fri Jun 22, 2012 7:50 am
I can speak to the USAF slick C-130 community 1992-2012. We have 3-engine data & procedures and the 3-engine takeoff is performed every year in the simulator (including all the associated subsequent emergencies). That said, I don't have any first hand knowledge of any AF slicks actually performing this maneuver in the span of my career. Special Ops may be another story.
All of the E & H models have direct-geared drives such that the prop will pinwheel in the wind (and turn the engine also) if the blade angle is right. As a result, there are two other maneuvers practiced annually in the sim: the Windmill Taxi Start and the Buddy Start. In short, set the blades to the optimum angle and, for the Windmill, perform a high-speed taxi (100 knots). The motor spins and the automatic starting sequence fires ... the engine doesn't care whether the starter is spinning it or if it's the wind. For the Buddy Start, have another Herk park very close and run up its engines. If the blast and blade angles are correct, the prop spins and the engine starts.
I mention these to say that all of these maneuvers involve some risk. The AF, in my experience, is extremely risk averse and rarely, rarely, rarely, authorizes even the optional starts. The Windmill was part of my AC & IP upgrades - I did several in the aircraft. They were not overly difficult. The Schoolhouse IPs do them every class. Still, they are not done operationally and I was told that it had everything to do with risk. In combat, with the bad guys coming over the wire, that's a different story - my crew briefed actions we would take to save ourselves and the aircraft; this included looking at our projected weight to see if a 3-engine takeoff would be possible or a known show-stopper. We would worry about explaining ourselves later.
There are two real problems with 3-eng ops - I can only speak to Herk performance. The airplane has to be light and conditions favorable. If nothing else breaks, you're fine. Realize that you start the takeoff run essentially 2 engine because the rudder and nosewheel steering cannot counteract the asymmetric thrust until Vmca is reached. As a result, power on the operating asymetric engine is fed in as rudder authority permits ... there is potential to run this thing off the side of the runway if you're not careful. If another motor coughs on takeoff or climbout (if climb gradient is a factor), you may not be able to continue flight. (That's if it feathers normally - if it doesn't you may be on your way to an immediate emergency landing at a place not of your choosing even sooner.) To give an example of performance, at local training weights, the Herk can be capable of around 6,000 on 2 engines but 22,000 on 3 - that's an appreciable difference. Due to asymmetric drag, rudder deflection and the like, losing 2 engines is not necessarily like "losing 50% of thrust", the net loss is more - same goes for 3-engine.
I never ran the numbers to quote, but to cruise on 3 saves some fuel, but if you need the speed, the other 3 need to be set at higher power settings to offset the engine that's feathered, so I always suspected that was one of the reasons the 2-engine cruise was abandoned (in addition to safety). Also, each engine has a hydraulic pump. If it happens to be both left-side engines you lose, now the gear and flaps have to be cranked. In short, there are a number of pitfalls that can cause real problems - an experienced crew and a fair amount of planning for contingencies is key.
The second problem is the FAA. I can't speak directly to Ferry Permits, but I know that some sort of permit/approval is required to operate an N-numbered airplane in such a configuration. Some companies arrange to do it with regularity, others avoid it like the plague. Thankfully, the news isn't littered with reports of accidents from these ops.
I don't have any B-17 time, but my overall position is that there is probably no good reason to 3-engine ferry such a rare airplane - the affects of another engine quitting (or other unforseen problem) may be catastrophic. I guess I'll log one more tenth on the soapbox. I was once told that "responsibility" can be looked at as "ability to respond" or "response ability". If you can't guarantee your response to the loss of another engine or that 2nd engine that fails to feather, or quits before you've accelerated to 2-engine Vmca, then it's hard to accept responsibility for a 3-engine takeoff. Sometimes, the need for mission accomplishment outweighs the responsibility for a 100% safe outcome, that's why it's done, but as for the decision to do or not to do, $hit does happen.
Ken
All of the E & H models have direct-geared drives such that the prop will pinwheel in the wind (and turn the engine also) if the blade angle is right. As a result, there are two other maneuvers practiced annually in the sim: the Windmill Taxi Start and the Buddy Start. In short, set the blades to the optimum angle and, for the Windmill, perform a high-speed taxi (100 knots). The motor spins and the automatic starting sequence fires ... the engine doesn't care whether the starter is spinning it or if it's the wind. For the Buddy Start, have another Herk park very close and run up its engines. If the blast and blade angles are correct, the prop spins and the engine starts.
I mention these to say that all of these maneuvers involve some risk. The AF, in my experience, is extremely risk averse and rarely, rarely, rarely, authorizes even the optional starts. The Windmill was part of my AC & IP upgrades - I did several in the aircraft. They were not overly difficult. The Schoolhouse IPs do them every class. Still, they are not done operationally and I was told that it had everything to do with risk. In combat, with the bad guys coming over the wire, that's a different story - my crew briefed actions we would take to save ourselves and the aircraft; this included looking at our projected weight to see if a 3-engine takeoff would be possible or a known show-stopper. We would worry about explaining ourselves later.
There are two real problems with 3-eng ops - I can only speak to Herk performance. The airplane has to be light and conditions favorable. If nothing else breaks, you're fine. Realize that you start the takeoff run essentially 2 engine because the rudder and nosewheel steering cannot counteract the asymmetric thrust until Vmca is reached. As a result, power on the operating asymetric engine is fed in as rudder authority permits ... there is potential to run this thing off the side of the runway if you're not careful. If another motor coughs on takeoff or climbout (if climb gradient is a factor), you may not be able to continue flight. (That's if it feathers normally - if it doesn't you may be on your way to an immediate emergency landing at a place not of your choosing even sooner.) To give an example of performance, at local training weights, the Herk can be capable of around 6,000 on 2 engines but 22,000 on 3 - that's an appreciable difference. Due to asymmetric drag, rudder deflection and the like, losing 2 engines is not necessarily like "losing 50% of thrust", the net loss is more - same goes for 3-engine.
I never ran the numbers to quote, but to cruise on 3 saves some fuel, but if you need the speed, the other 3 need to be set at higher power settings to offset the engine that's feathered, so I always suspected that was one of the reasons the 2-engine cruise was abandoned (in addition to safety). Also, each engine has a hydraulic pump. If it happens to be both left-side engines you lose, now the gear and flaps have to be cranked. In short, there are a number of pitfalls that can cause real problems - an experienced crew and a fair amount of planning for contingencies is key.
The second problem is the FAA. I can't speak directly to Ferry Permits, but I know that some sort of permit/approval is required to operate an N-numbered airplane in such a configuration. Some companies arrange to do it with regularity, others avoid it like the plague. Thankfully, the news isn't littered with reports of accidents from these ops.
I don't have any B-17 time, but my overall position is that there is probably no good reason to 3-engine ferry such a rare airplane - the affects of another engine quitting (or other unforseen problem) may be catastrophic. I guess I'll log one more tenth on the soapbox. I was once told that "responsibility" can be looked at as "ability to respond" or "response ability". If you can't guarantee your response to the loss of another engine or that 2nd engine that fails to feather, or quits before you've accelerated to 2-engine Vmca, then it's hard to accept responsibility for a 3-engine takeoff. Sometimes, the need for mission accomplishment outweighs the responsibility for a 100% safe outcome, that's why it's done, but as for the decision to do or not to do, $hit does happen.
Ken
Last edited by Ken on Fri Jun 22, 2012 10:05 am, edited 4 times in total.
Re: b-17 left teterboro on 3 engines last night?
Fri Jun 22, 2012 8:21 am
Ken, that information is golden. Just an example of one of the many reasons I love this forum!
Zack
Zack
Re: b-17 left teterboro on 3 engines last night?
Fri Jun 22, 2012 3:35 pm
Ken wrote:All of the E & H models have direct-geared drives such that the prop will pinwheel in the wind (and turn the engine also) if the blade angle is right. As a result, there are two other maneuvers practiced annually in the sim: the Windmill Taxi Start and the Buddy Start. In short, set the blades to the optimum angle and, for the Windmill, perform a high-speed taxi (100 knots). The motor spins and the automatic starting sequence fires ... the engine doesn't care whether the starter is spinning it or if it's the wind.
I knew a guy that used to do this on occasion in DC-6s and 7s when he was flying for the non-scheduled airlines (I think he flew for Slick Airways among others). If they had an engine that wouldn't start, they would offload the passengers, do a windmill start, and then reload the passengers with that engine still running. Probably not too confidence inspiring for the passengers, but things were different back then.
Re: b-17 left teterboro on 3 engines last night?
Fri Jun 22, 2012 8:19 pm
Ken, that 'buddy start' thing is something I'd never heard of before - fascinating. Thanks to all for a great discussion, most edumacational.
James the Mudgely edumacated.
James the Mudgely edumacated.
Re: b-17 left teterboro on 3 engines last night?
Fri Jun 22, 2012 9:14 pm
In my QC days @ Renton with Boeing, part of every Inspectors required annual reading was to be familiar on procedures to launch two, three, or four engined aircraft with fewer than the required complement of engines. One engined 737-200's, two engined 727-200's, and three engined E3A's in case the flag went up.
Always pondered the chances of a single engined 737 with 1 JT8D getting out of Renton and not becoming a seaplane.
Always pondered the chances of a single engined 737 with 1 JT8D getting out of Renton and not becoming a seaplane.
Re: b-17 left teterboro on 3 engines last night?
Fri Jun 22, 2012 9:44 pm
mustangdriver wrote:I think everyone agrees that it can be done. I think a better question is SHOULD it be done. Should you DEPART knowing you only have three engines. My vote is no. I also am interested to know if it is even legal.
Call the operators and ask them to send you a copy of their operating specifications for the airplane because you want to write a bunch of stuff on an internet forum about your opinion about their operation and see what you get.
Chris...
Re: b-17 left teterboro on 3 engines last night?
Sat Jun 23, 2012 7:21 am
WHats a windmill start?
Re: b-17 left teterboro on 3 engines last night?
Sat Jun 23, 2012 8:01 am
Not to stray too far OT for JDK ...
There are a few situations that call for the Buddy or Windmill. The first step to any of these (in a Herk) is to think ahead and, prior to removal of power to the aircraft (APU, engine generator, power cart), to preposition at least one of the props to the optimum blade angle we call "on the cuff". The motor which provides hydraulic pressure to the prop is AC powered and, should you subsequently lose the ability to get AC power, you'll wish you'd pre-set the blades. It's common to cuff a prop when shutting down at a forward location or anyplace you think maintenance/support is nonexistent as most of our ops there are internal/APU only. The blades are commanded to move and stopped when the black Lockfoam cuff aligns with the matching lands molded into the spinner assembly.
This crew has elected to "cuff" both inboards and the high pitch is evident. (photo by Joe Houston)
Now, if the APU fails to start, (and there is no maintenance or air-start cart) a Buddy start can be performed with another Herk and your ship's battery only. Once that first motor is running, then that engine's AC generator can power the plane and provide the bleed air to spin the remaining three.
Another contingency is that you have a single failed starter or failure of the bleed air system to supply pressure to an individual engine. Place the affected engine on the cuff and arrange for a Buddy start; hopefully this avoids a 3-engine takeoff. This situation is also a reason to perform the Windmill ... which I prefer because you don't need a Buddy and the total pain involved is much less versus the wind blast, FOD hazards, etc of the Buddy. Interestingly, one of the sim scenarios is to not have time for a Windmill (the enemy is arriving) and to perform a 3-engine takeoff followed by an airstart of the engine with the broken starter. Another diabolical scenario would be to do a Buddy start an engine and to have a remaining problem on another engine which then leads to a 3-engine takeoff. You gotta hand it to those sim IPs.
Anyway, I digress. Windmill, Buddy, 3-engine takeoff, airstart. Each a different tool for the toolbox, not sure of the direct applicability to a B-17, but a little insight into 4-engine ops.
Ken
There are a few situations that call for the Buddy or Windmill. The first step to any of these (in a Herk) is to think ahead and, prior to removal of power to the aircraft (APU, engine generator, power cart), to preposition at least one of the props to the optimum blade angle we call "on the cuff". The motor which provides hydraulic pressure to the prop is AC powered and, should you subsequently lose the ability to get AC power, you'll wish you'd pre-set the blades. It's common to cuff a prop when shutting down at a forward location or anyplace you think maintenance/support is nonexistent as most of our ops there are internal/APU only. The blades are commanded to move and stopped when the black Lockfoam cuff aligns with the matching lands molded into the spinner assembly.
This crew has elected to "cuff" both inboards and the high pitch is evident. (photo by Joe Houston)
Now, if the APU fails to start, (and there is no maintenance or air-start cart) a Buddy start can be performed with another Herk and your ship's battery only. Once that first motor is running, then that engine's AC generator can power the plane and provide the bleed air to spin the remaining three.
Another contingency is that you have a single failed starter or failure of the bleed air system to supply pressure to an individual engine. Place the affected engine on the cuff and arrange for a Buddy start; hopefully this avoids a 3-engine takeoff. This situation is also a reason to perform the Windmill ... which I prefer because you don't need a Buddy and the total pain involved is much less versus the wind blast, FOD hazards, etc of the Buddy. Interestingly, one of the sim scenarios is to not have time for a Windmill (the enemy is arriving) and to perform a 3-engine takeoff followed by an airstart of the engine with the broken starter. Another diabolical scenario would be to do a Buddy start an engine and to have a remaining problem on another engine which then leads to a 3-engine takeoff. You gotta hand it to those sim IPs.
Anyway, I digress. Windmill, Buddy, 3-engine takeoff, airstart. Each a different tool for the toolbox, not sure of the direct applicability to a B-17, but a little insight into 4-engine ops.
Ken