60 drivers, got a question

[akscott60]

When you droop your rotor and go to "lockout"...

 

A. What does lockout mean?

 

B. What does it give you?

 

I have a rough general idea, but I would like specifics if able.

 

Thanks.

Edited April 6, 2013 by akscott60

[Shenanigan]

I'm assuming your not a hawk driver? Are you asking because of the aircraft that crashed when going into lockout in Afghanistan?

 

Basically the engines are governed by a computer similar to other aircraft. Lockout bypasses that computer governing and the pilot controls engine rpm manually by moving the Power control levers which are just throttles (one for each engine). When the computer is governing the engine it will not allow the engine to exceed a TGT limit. In lockout that limit can be exceeded.

 

The purpose of lockout is for malfunctions in that computer some EPs tell the pilot to lock the engine out and manually control it. It's not really meant to be used to bypass TGT limits but every hawk pilot knows that if the situation were dire enough they could go to lockout and get more power to get the rotor up to speed. This could damage the engine and possibly the transmission though. However at low temperatures the engine is limited by NG or max fuel flow and going to lockout will not yield more power because those limits are in the HMU not the computer.

[akscott60]

Haha. Double bingo. Yea, I fly Kiowas. We have limit override logic built into our FADEC system. If we are in a transient and droop the rotor the engine will literally kill itself to let us survive.

 

Like 160% Ng or a billion % Tq. Whatever she needs to survive.

[Shenanigan]

Yeah I just saw that video. In response to that our -10 was changed and now explains NG limiting a little better. It used to be something that received very little attention so they want to make sure pilots understand that lockout will not do anything for power under NG limiting. I wish we had a Fadec system that allowed us to override it temporarily but I guess the engineers figured it wasn't a good idea. I heard a Lakota will put a mark on whatever gauge is limiting the aircraft. We can only tell by the charts.

 

So for TGT limiting we know will always be 866 and we can look at the gauge and know when the rotor will droop but NG limiting could be anywhere from 93-103 depending on conditions and you only know where the approximate torque is by doing the PPC.

 

Those guys were limited by NG so lockout didn't help them. They should have known from the PPC but hey, sometimes we all do dumb things.

[Velocity173]

Hey akscott, does the 58 still have NP limiting when you revert from FADEC to manual?

[akscott60]

We have NP over speed protection always. 124-118%. I've heard it's like flying in a paint mixer when its bouncing between those numbers.

Edited April 6, 2013 by akscott60

[Velocity173]

We have NP over speed protection always. 124-118%. I've heard it's like flying in a paint mixer when its bouncing between those numbers.

Ok it's like the Hawk in that you have a limit. 106 % for an A and 120 % for a L. You can let it hit the limit all day long in an A and not break anything. In a L you you're going past a -10 limit and you gotta write it up. I've hit 117 % NP by accident but the MTP checked his numbers and said no maintainence action was required.

[akscott60]

If we get into NP overspeed protection we have already exceeded a limitation 107-112% NP for 15sec.

 

We have NP overspeed to keep a runaway rotor from flying off my itself. Haha

[d10]

DEC lockout isn't meant for pilot induced rotor droops. It's only supposed to be used in the event of a DEC malfunction that's limiting engine power. The mechanical engine power control levers are set at full throttle during normal operation and the DEC has the authority to reduce fuel flow based on rotor speed, collective position, and the output of the other engine to constantly maintain a reasonable power output. It's possible for a malfunction to occur which leads the DEC to believe it needs to restrict fuel flow way more than it actually should, leaving you with a very weak or completely useless engine. This is where you would put the engine in lockout, allowing the fuel flow to be controlled solely through the mechanical components.

 

The DEC also uses it's control authority to limit fuel when TGT reaches the limiter, so going into lockout has become an unofficial means of bypassing this function and giving yourself extra power in a pilot induced emergency. This technique isn't supported by any of our manuals and I think it's a terrible practice. A reduction in collective, a control which you already have in your hands, will get your rotor back faster than reaching for an engine power control lever and putting it in lockout. If you've reached a point where it's DEC lockout or crash, you've really been flying poorly.

[Velocity173]

Yep, agree with D10. If you've reached a DA situation where you need lockout to avoid a crash, you did some poor planning. In that situation, lockout probably isn't going to save your butt either. I've drooped the rotor at 8,000 ft in the middle of summer in Afghanistan but I had a bailout. No need to do lockout. Just reduce collective, go around and come back in at a different direction. Sometimes we max perform the aircraft, but you always, always need a bailout.

[Shenanigan]

DEC lockout isn't meant for pilot induced rotor droops. It's only supposed to be used in the event of a DEC malfunction that's limiting engine power. The mechanical engine power control levers are set at full throttle during normal operation and the DEC has the authority to reduce fuel flow based on rotor speed, collective position, and the output of the other engine to constantly maintain a reasonable power output. It's possible for a malfunction to occur which leads the DEC to believe it needs to restrict fuel flow way more than it actually should, leaving you with a very weak or completely useless engine. This is where you would put the engine in lockout, allowing the fuel flow to be controlled solely through the mechanical components.

 

The DEC also uses it's control authority to limit fuel when TGT reaches the limiter, so going into lockout has become an unofficial means of bypassing this function and giving yourself extra power in a pilot induced emergency. This technique isn't supported by any of our manuals and I think it's a terrible practice. A reduction in collective, a control which you already have in your hands, will get your rotor back faster than reaching for an engine power control lever and putting it in lockout. If you've reached a point where it's DEC lockout or crash, you've really been flying poorly.

I know an instructor pilot who was taking off and at about 50 feet he was over a road with wires and had trees 100 feet tall in from of him when he lost the number two engine. A reduction in collective would have just caused a crash into the wires or trees so he went to lockout, TGT maxed out on the gauge and he cleared the trees and came around for a roll on.

 

There are certainly many situations where an engine failure at the right moment would not allow for a reduction in collective and the right move would be to go to lockout to exceed the limiter.

[Velocity173]

I know an instructor pilot who was taking off and at about 50 feet he was over a road with wires and had trees 100 feet tall in from of him when he lost the number two engine. A reduction in collective would have just caused a crash into the wires or trees so he went to lockout, TGT maxed out on the gauge and he cleared the trees and came around for a roll on.

 

There are certainly many situations where an engine failure at the right moment would not allow for a reduction in collective and the right move would be to go to lockout to exceed the limiter.

Where was this at? He departed into rising terrain? There aren't many engine failures in 60s and the odds of having one below SE airspeed is pretty slim. While we had many SE failures at Rucker in A models, I've only met one guy who had one in a L and he just happens to be the only one who's had a dual engine failure in a Hawk. So you'd have to have one below SE airspeed (generally ETL) and just happen to have nowhere to set it down. For the vast majority of arrivals and departures you can set up a profile to either fly away SE or set it down with no damage.

 

Almost every airport, base, FOB, COP or whatever I've departed from, I could either set it down or fly out. Proper planning. Only time I've worried about an engine failure is doing resupplies to a ridge line. If it happens then no lockout is going to give you enough power to maintain a hover at an 8,000 ft. You're screwed. Even then, the chances of that happening are so remote it's not even worth bring up.

[Shenanigan]

Where was this at? He departed into rising terrain? There aren't many engine failures in 60s and the odds of having one below SE airspeed is pretty slim. While we had many SE failures at Rucker in A models, I've only met one guy who had one in a L and he just happens to be the only one who's had a dual engine failure in a Hawk. So you'd have to have one below SE airspeed (generally ETL) and just happen to have nowhere to set it down. For the vast majority of arrivals and departures you can set up a profile to either fly away SE or set it down with no damage.

Almost every airport, base, FOB, COP or whatever I've departed from, I could either set it down or fly out. Proper planning. Only time I've worried about an engine failure is doing resupplies to a ridge line. If it happens then no lockout is going to give you enough power to maintain a hover at an 8,000 ft. You're screwed. Even then, the chances of that happening are so remote it's not even worth bring up.

It was at Lowe in north hover departing to the north.

 

We operate the aircraft in a profile that would not allow for a reduction of collective almost every day. Any departure from a confined area, fastropes in urban environments or over terrain that wouldn't allow a landing, nearly all hoist operations, at times during NOE, and any other maneuver OGE over terrain or when above critical torque. You simply cannot operate an army helicopter in the ways required by always staying below critical torque over terrain that won't allow a landing. I'll agree that prior planning allows us to minimize those opportunities but we can't eliminate them.

 

As for the likelihood, I've known many pilots who've had a single engine failure during their career. I would say that it is one of the more likely EP's we have even though it is still rare.

[Velocity173]

As I said an A at Rucker has a slight chance of that happening. Still locking out an A is only going to give you a whopping 106 % NP. Im sure that wasn't the difference between crashing and flying. Plus if he wasn't above ETL prior to leaving the fence in North Tracking he did a poor departure. Send me his name so I can make fun of him.

 

I'd like to know all these pilots you talk of who had engine failures in 60s. 3,700 hrs in As & Ls and I never even had one cough. At 3 different duty stations none of my friends lost an engine either. Even during the 4 yrs at Rucker we had maybe 3 while I was there. Odds are slim.

 

Lockout isn't a magical wand that will allow you to hover OGE on one engine. In the extremely rare case the engine fails at less than SE flight, lockout may or may not support flight. You're probably still coming down, now it's on a torched engine. Out of the examples you gave the OGE stuff is about the only time lockout might work. That's covers about 1 % of the time you spend flying. NOE? Maybe 20 yrs ago but no one is doing it today in a 60 unless they're screwing around.

 

Also just because you're above critical TRQ doesn't mean you're going to lockout on the other engine. in combat we flew above critical the majority of the time at cruise flight. If any of my guys can't recover the aircraft after a failure at 130 kts, then they shouldn't be flying the aircraft.

[d10]

To be fair, 106% NP = 106% NR no matter how the power is made which should be good enough to fly anywhere within the Hawk's normal service ceiling. Confined area departures and anything above critical torque is still a poor excuse for needing lockout though. I can see doing it for hoists and fast ropes but like you said, being in that profile is rare and engine failures (especially without a large change in collective) are even more rare. Plus you're getting your TGT limit bumped up automatically with an engine failure to the emergency limiter. I'm not sure how safe it is to go beyond that on your last good engine, so it would really need to be a last resort. I still have a problem with guys briefing before missions that they're going to go to lockout whenever they get into a situation where they run out of power. I think it's a crutch that will get you into more trouble than it saves you from.

[Shenanigan]

As I said an A at Rucker has a slight chance of that happening. Still locking out an A is only going to give you a whopping 106 % NP. Im sure that wasn't the difference between crashing and flying. Plus if he wasn't above ETL prior to leaving the fence in North Tracking he did a poor departure. Send me his name so I can make fun of him.

I'd like to know all these pilots you talk of who had engine failures in 60s. 3,700 hrs in As & Ls and I never even had one cough. At 3 different duty stations none of my friends lost an engine either. Even during the 4 yrs at Rucker we had maybe 3 while I was there. Odds are slim.

Lockout isn't a magical wand that will allow you to hover OGE on one engine. In the extremely rare case the engine fails at less than SE flight, lockout may or may not support flight. You're probably still coming down, now it's on a torched engine. Out of the examples you gave the OGE stuff is about the only time lockout might work. That's covers about 1 % of the time you spend flying. NOE? Maybe 20 yrs ago but no one is doing it today in a 60 unless they're screwing around.

Also just because you're above critical TRQ doesn't mean you're going to lockout on the other engine. in combat we flew above critical the majority of the time at cruise flight. If any of my guys can't recover the aircraft after a failure at 130 kts, then they shouldn't be flying the aircraft.

His name was Osterhaus, make fun of him if you'd like. I would not consider his decision to do a present position departure to be unusual, I would not consider the authorization he received from ATC for that departure to be unusual and I would not consider the flight profile he was in to be unusual. He was performing a maneuver that is not only in the task list but is required to be trained in an altitude over airspeed takeoff. He was briefed to perform the maneuver, in fact I have never heard of an aviator being briefed that they must maintain the aircraft in a profile that allows for single engine performance in all modes of flight. I think the suggestion that you or anyone else do not routinely operate your aircraft in those profiles to be hard to believe.

 

I don't understand why you would bring up NP speed when it is not indicative of power and does not represent the problem in this case which would be a lack of TQ.

 

Both in the 700 and 701 the 12 second transient torque can only be obtained in lockout. Use of this in the right emergency situation would not only be smart and safe but I would argue that it would be required by chapter 9 under the note that helicopter control is the most important requirement in an emergency and all steps are subordinate. I think I can safely say that most pilots would agree with me and would have done exactly what Mr. Osterhaus did. Since we all know that a 14,500lb UH-60A is not capable of an OGE climb on one engine I would say that the increase in TGT added a significant amount of TQ and was exactly what stopped the aircraft from crashing, probably saving the lives of those on board.

 

I would consider nearly one engine failure per year just at Rucker to be common enough that people should know what to do. All EPs are unlikely, there is an even smaller chance of needing to autorotate but we still train to do it. The chance of an engine failure or high speed shaft failure is probably highest when the engines are operating at high power like in an OGE hover.

 

Nobody is suggesting that lockout is a cure all or a planning tool but I would expect any pilot to be able to identify when the aircraft is in TGT limiting and identify when it's their only chance at saving the aircraft in an emergency. I do not agree that Army aviators can operate their aircraft at all times in a profile that allows for a fly away in the event of an engine malfunction.

[Synixman]

Do you guys have a Contingency Power switch on the collective like Navy birds? We can go to 891 plus or minus 10 to get extra power if we need it with the switch. We brief using it for all HOGE maneuvers and first takeoff of the day, plus other cat and dog times. We have 701Cs in our S model, so we have pretty good power, even though we're heavy as sh*t most times with all the stuff they've put in there.

 

And I'm with d10. Lockout is, for us, an emergency use only item. We'd only use it for a low side failure where the DECU is trimming the HMU down too far. We'd get to safe single engine speed first before touching it. Planning on using it is a terrible idea.

[Velocity173]

Well I was implying to PM his name but whatever. I worked a short stint on nights with him. One of the best IPs at Lowe actually. Still didn't need to go to lockout though.

 

No, NP isn't an indicator of power, it's an indicator of maintaining RPM and that's the whole point of locking out. Also just because in lockout the engine is limited at 106 %, doesn't mean it's going to go there. If you're heavy enough and pulling a crap load of TRQ, drag is going to pull down the rotor regardless of lockout. It's not an automatic I'm gonna give you 106 % rpm switch. In the North Tracking incident he probably did get 106 out of it but that's a light Hawk in forward flight.

 

No one is saying we always avoid profiles outside the avoidance area. What I'm saying is just because you're in it doesn't always mean to lockout. I agree with D10 that hoist or any case where people are dangling from the aircraft, lockout might be a viable option. I disagree that there are " many situations" that would require lockout.

 

I'm not sure if you're joking about a 14,500 lb A not being able to maintain an OGE climb but that's way off. At Rucker you have roughly between 20-120 kts for your SE window. Anything greater than 20 and less than 120 you have excess power. At 65 kts or around max rate / end you'll have about a 30 % excess in TRQ on that engine. Plenty of power to climb. I used to pull an engine back on students just after clearing the trees and going through ETL out of an RT. They found that not only can the aircraft maintain flight, it can accelerate and climb out quite swiftly. I've also flown an entire patern in Bagram (5,000 DA) on one engine in a 16,000 lb Hawk. 300 FPM at 65 kts isn't much but it'll get you out of a hot area without doing further damage to your aircraft. I even had an IP during my progression who would retard an engine at 150 ft hover. I found an aggressive nose down and reduction in collective would have me through ETL by the time I hit 50 ft and was easily flying out of it by 15-20 ft. Anything less than a 100 ft hover, you're probably going to have to eat it, but most likely without injuries.

 

I don't mind a belief in lockout can save your bacon in rare cases, but it shouldn't be briefed a procedure for all cases of lack of power. Proper planning and proper control inputs will suffice the majority of the time.

[akscott60]

This topic is good.

[Shenanigan]

You cannot seriously believe that I was using the term OGE in reference to cruise flight. I feel like you are being argumentative just for the sake of being argumentative at this point. I agree with your last paragraph, that was my point.

 

I feel that statements like "lockout is only for ECU/ DEC malfunctions", "You should not operate in a profile that won't allow for single engine capability", and "The chance of a single engine failure is so remote that we don't need to worry about it." are untrue. We should be striving to make technical experts, not simply giving people overly simplistic rules to follow blindly.

[d10]

We should be striving to make technical experts, not simply giving people overly simplistic rules to follow blindly.

 

I think we're making the same point then. I'm not advocating flying an aircraft into the ground if you have another option. I'm against people planning on using lockout as early as their preflight brief. That's become common enough that someone in another airframe asked about lockout as if that's your immediate response when you droop your rotor. And for a lot of 60 pilots it is.

[SBuzzkill]

What percentage of UH-60 crashes would you say could have been prevented by using lockout? Putting aside the lack of aviating that got the crews into the situation.

 

I ask because we have had crashes where the crews did not use the available limit override logic when it would have gotten them out of the situation they were in.

Edited April 7, 2013 by SBuzzkill

[Velocity173]

What percentage of UH-60 crashes would you say could have been prevented by using lockout? Putting aside the lack of aviating that got the crews into the situation.

 

I ask because we have had crashes where the crews did not use the available limit override logic when it would have gotten them out of the situation they were in.

I really think with all the variables involved its too hard to say. How many SE failures have happened in 60s that even required lockout? Millions of hours flown and I don't know of any that happened while doing hoist, sling loads or any other OGE hover type operations. I'm sure there are a few out there but I can't recall any.

 

You could say the 160th Mt Massive accident a few years ago might have been prevented with lockout. Anyone who flys 60s is familar because it was in the ACT-E a couple years ago. They were in a definite situation where they didn't have the power to perform a pinnacle landing at 14,000 ft. Would lockout have made the difference? Really it's impossible to tell.

 

So basically you'd have to have some real data that shows 1. Number of engine failures or dual engine lack of power resulting in crashes 2. Hard data that indicates a SE lockout or dual engine lockout would have definitely provided enough power to save the aircraft.

[d10]

It's also hard to say because the large majority of power related 60 accidents can be attributed to pilot error rather than mechanical failures. Going to lockout still requires pilot action, so you'd have to look at how many people failed to manage their power properly to begin with but had the presence of mind to put the engines in lockout to make up for it. And if we're just looking at accidents that could have been prevented by going to lockout, that's assuming none of those pilots actually went to lockout. If you're trying to make a case that more pilots should be taught to think lockout when they're faced with insufficient power, I would argue that their efforts are better spent thinking power management, planning practical escape routes as often as possible, and reacting quickly to rotor droops with a reduction in collective and getting to a flight profile that requires less power. If you just want to know how many accidents could have been prevented if the pilots just had more power available without any action required on their part, probably a lot, but that's not how the system works.

 

I know of at least one accident that could have been prevented if the pilot went to lockout. But it could have been prevented much more easily by not pulling in an armfull of collective to go around when he got frustrated he couldn't find the one-wheel landing spot his crew chief was calling him into. Nobody says "They should have gone to lockout" about that one.