V1 in small twins

[pelmet]

I think it would be better if pilots only used the term V1 for aircraft that actually have a published V1 speed(s). Otherwise, it can cause great confusion for newer pilots just learning about this stuff.

[Big Pistons Forever]

The TC AIM defines V1 as " Critical Engine Failure Recognition Speed"
and then adds the following note

This definition is not restrictive. An operator may adopt any other definition outlined
in the aircraft flight manual (AFM) of TCtype-approved aircraft as long as such definition
does not compromise operational safety of the aircraft.

Therefore I would suggest that while the traditional V1 speed is before Vr it does not have to be and therefore is relevant to this topic.

[pelmet]

Therefore I would suggest that while the traditional V1 speed is before Vr it does not have to be and therefore is relevant to this topic.

Aircraft that have V1 speeds(which are not small twins) cannot have a V1 speed greater than VR speed. The pilot may decide to abort at a speed higher than VR but it is also above the V1 speed which has nothing to do with 'small' twins anyways

[cncpc]

I flew 400 hours on a Seminole and if I remember correctly, it wasn't a speed we were concerned with, but the position of the landing gear. If the gear was down, we would cut power and land straight ahead. If the gear was up, we would continue a shallow climb and initiate the engine failure procedure. Most of the time we had a ton of runway to spare and I'd rather risk a runway excursion than try climbing on one engine in that thing.

Back in the day, I used to fly a Seminole in northern BC. In a flight where a radio tech had to be taken to a forestry repeater, we landed on a road and damaged a prop sitting in the spot off road we taxied to. The road at Takla Landing. AME flies out in another aircraft in the morning and does some work on the prop, says it's good to go. I questioned the procedure to balance the work done on the one blade with the other. I was told it would be fine.

The tech's toolbox and the AME's tool box go with me. The tech and the AME and pilot get in the 172 and take off first. I take off, hit the gear immediately, look at the repaired side prop, and the spinner tip is making a circle about four inches in diameter. Very noticeable vibration. Make sure I've got the right mixture knob, pull it back to cutoff, and feather. Engine is still in the mounts. But, it climbs fine on the one. Probably about 300 under gross. Climbed to 5500 to join the 172, and it flew fine. We flew right over Fort St. James, and back to base at Prince George. 165 miles, no problem staying with the 172.

Towed it off the taxiway as it was shite for taxiing on one engine. There was some damage to the mount.

[tsgarp]

The tech's toolbox and the AME's tool box go with me. The tech and the AME and pilot get in the 172 and take off first.

Dude didn’t want to fly in the aircraft he worked on? Bad juju.....really bad juju.

[cncpc]

The tech's toolbox and the AME's tool box go with me. The tech and the AME and pilot get in the 172 and take off first.

Dude didn’t want to fly in the aircraft he worked on? Bad juju.....really bad juju.

I'm not sure what his thinking was, but I am sure he believed the work was adequate. We have remained good friends for almost 40 years.

I have to say that it did not require max flying skill once it was feathered. That took about five seconds. I was surprised at its climb performance. Had a "Why the hell did he do that" moment when we passed over the airport at Ft. St. James, imagining what the AvCanada of the day folks would say if the other one had quit, but it was pretty well like flying a single wing low with a bit of rudder trim. A small bit of above cruise power, but not near max.

I posted this for the lad above who was worried about the one engine climb performance of the Seminole. But, just one experience, and it was not at gross. All up, may well be a different story.

[youhavecontrol]

I posted this for the lad above who was worried about the one engine climb performance of the Seminole. But, just one experience, and it was not at gross. All up, may well be a different story.

My previous post was more to do with climb performance on one engine based on the landing gear's position. With the gear down at less than 50 feet, with the time it takes to identify and feather the bad engine... there's a lot going on. Your example states you raised the gear immediately on take-off, so what you did in your example is exactly what I would have done at the point of failure with the already gear up... kept climbing.

Having done this exact scenario with my students in the simulator at approx 30'AGL with the gear still down... ALL of the ones that cut the power and landed straight ahead did just fine and did not over-run the runway, and around 95% of the ones that tried to keep flying could not maintain directional control while trying to feather the bad engine and keep a safe speed, and crashed.

This lad has questions, if I'm honest. How did the AME test that the prop was balanced exactly and how did you verify that before you took-off? Did you do a run-up, feather check or governor check? You mentioned you immediately raised the gear... was that standard practice or did you modify your procedure given the suspicion of engine failure? Was it necessary to fly 165 miles back to base on one engine in the mountains? Was Smithers or Terrace not an option to get on the ground sooner?

[iflyforpie]

Smithers is over one set of mountains and Terrace is over two with not much in between.

Prince George is following shallow valleys and short mountain until you reach the plateau and you have Ft St James for a diversionary field if things go south plus the BC Rail right of way the whole way there.

It’s what I would have done.

[pelmet]

.

[pelmet]

I posted this for the lad above who was worried about the one engine climb performance of the Seminole. But, just one experience, and it was not at gross. All up, may well be a different story.

Bit of a story about light twins on one engine.......

My experience climbing with a feathered engine was not so good. I was doing my multi-IFR in a Duchess with an instructor at night. The school was based at a small airport and we were about 15 miles away doing approaches at the big airport with long runways. During a procedure turn, the instructor said that he might have seen some sort of a glow like a fire under the left engine and asked me to take a look. I said that everything looked normal. Then he took control and started banking back and forth as if that might somehow help him see under the wing better but subsequently seemed satisfied that everything was OK. So we continued the procedure turn with me going back under the hood.

We intercepted the ILS and started descending for our ten thousand foot runway. At about 800 feet or so, the instructor says HOLY S__T, and the next thing you know, the engine he was concerned about has been feathered. All this because he thinks we have a fire. Then he tells me to go-around which I foolishly do and he advises ATC that we are finished our training and would like to head back to the airport where the school is based(obviously for convenience). So potential fire, nice runway ahead, one engine shutdown and we are going to a different airport with no emergency declared and no emergency equipment. I really should have said something about landing straight ahead on the nice big runway but flew the go-around as instructed.

With just two of us on board and somewhat cool temperatures, I remember quite poor climb performance and any sloppy flying on my part with speed excursions above or below the blue line had a significant detrimental effect on performance. I remember struggling to climb to 1700'.

Anyways, we landed and had the airplane checked and of course, no faults found. Perhaps the beacon or a ground light caused the concern. I also remember that the mechanic wanted the engine unfeathered so the instructor started up the engine and it causes quite a bit of vibration in the aircraft while the propeller unfeathers. I am still not sure if that is something that is OK to do.

[youhavecontrol]

Smithers is over one set of mountains and Terrace is over two with not much in between.

Prince George is following shallow valleys and short mountain until you reach the plateau and you have Ft St James for a diversionary field if things go south plus the BC Rail right of way the whole way there.

It’s what I would have done.

Ah ok that makes sense.

[digits_]

I also remember that the mechanic wanted the engine unfeathered so the instructor started up the engine and it causes quite a bit of vibration in the aircraft while the propeller unfeathers. I am still not sure if that is something that is OK to do.

For what it's worth, I've also been asked to do that once. On a piston engine only of course, for turbines it's a bit more critical, depending on how hey are designed to work.

[pelmet]

I also remember that the mechanic wanted the engine unfeathered so the instructor started up the engine and it causes quite a bit of vibration in the aircraft while the propeller unfeathers. I am still not sure if that is something that is OK to do.

For what it's worth, I've also been asked to do that once. On a piston engine only of course, for turbines it's a bit more critical, depending on how hey are designed to work.

Some turbines, you can feather and unfeather while the engine is stopped using an electric pump. Bit off topic though.

[cncpc]

This lad has questions, if I'm honest. How did the AME test that the prop was balanced exactly and how did you verify that before you took-off? Did you do a run-up, feather check or governor check? You mentioned you immediately raised the gear... was that standard practice or did you modify your procedure given the suspicion of engine failure? Was it necessary to fly 165 miles back to base on one engine in the mountains? Was Smithers or Terrace not an option to get on the ground sooner?

The prop wasn't balanced exactly. It was a field repair at the side of a forestry road in the wilderness. That engine was run up after the repair, and again with the other one in a standard run up with all the power checks, but at run up RPM. It was a gravel road and a gravel pull off.

I raise the gear once there is insufficient runway ahead to land. This was a road with trees at the "departure end". There is a strip built near there since, but that road had been used as an airstrip for quite a few years. Balanced field length was not available. In those circumstances, as soon as the wheels are off and climb is established, I touch the brakes and raise the gear. I agree that was critical to the outcome.

I start every takeoff with a suspicion of engine failure. In this case, the engine didn't fail. It was shut down as a precaution against it coming out of the mount. Which it likely would have done if takeoff power had been maintained.

There was an ongoing discussion with the other aircraft that began right after the shutdown. The choices were influenced by the good performance on one engine and its ability to maintain 5500 with gauges in the green and normal cruise power. In some circumstances, it was possible to have started the shut down engine and using it at reduced power, but it would not have been usable on a restart because the other one had failed. Outs at Burns Lake, Ft. St. James, Vanderhoof, but as the flight progressed over or near to those points, it was never in difficulty and it was decided to go to Prince George, which was our home base. I considered a restart for the landing, but decided to not complicate things. No emergency was declared, but I did advise XS tower that I had one shut down. You can fly that route at 3500 feet. As IFly says, it's a plateau. It may be shorter to Smithers, but there is higher terrain in the way.

I've found that log book. I see it was Leo Creek on Takla Lake, and not Takla Landing. There is a 2500 foot bush strip there now, right where the road used to be, and they've cut down the trees at the northwest end. The log book says 120 miles S.E. but I see it's 140.

It was a normal takeoff until it wasn't. Then there was a new normal in which the aircraft performed as advertised. It took off, some things happened, and it landed without incident. I see it's still flying in Ontario.

[co-joe]

...

Same for a king air class kind of airplane. They are great performers. Why treat V1 as a life and death decision on a long runway? If you have 10 000 ft and something happens, even past v1, why not abort?

It just drives me bonkers. Discussing it with management or training pilots, even crew members always results in "But it's V1, it's the decision speed, you can't abort past V1!".

Thoughts? Am I missing something?

If you really want to calculate a legal and true V1 for King Airs, there's a program for the Ipad called I Preflight, it's put out by Aerodata, and you can do full balanced field, and net takeoff flight path calculations for King Airs, possibly even Navajo. The problem is, most of the aerodromes you operate King Airs out of wouldn't meet the requirements for ASDA, TODA, and TORA. If TC ever mandated balanced field for 703 most aerodromes would become illegal. Hell if TC ever ran the numbers for 704 ops, they'd realise there are lots of companies in Canada not playing by the rules.

Fact is, if you have an engine failure before Vr in a Beech, you might die, if you lose one after Vr and get airborne, you still might die...welcome to 703 aviation.

[goingnowherefast]

I've seen published balanced field and performance data for a King Air with V1, V2 and all. IIRC, it was in the back of a B200 Raisbeck supplement. The numbers weren't fantastic, 5000-7000', depending on conditions, flap setting, load, etc. Certainty didn't consider runway conditions, cause compact snow is the same as bare, dry pavement....

[rxl]

I think it would be better if pilots only used the term V1 for aircraft that actually have a published V1 speed(s). Otherwise, it can cause great confusion for newer pilots just learning about this stuff.

AGREED. How can you have a takeoff decision speed in an airplane that doesn’t have to guarantee the performance capability to continue that takeoff after the failure of the critical engine? What decision is there? The rocks or the trees I suppose.

[Alex335]

I raise the gear once there is insufficient runway ahead to land.

Why would you wait for insufficient runway in a twin? People do that in single usually.

On the piston twin I fly, and all the piston twin POH/AFM I’ve read called for gear up @ positive rate. Leaving the gear down just leaves you exposed, usually these aircraft won’t climb gear down near MTOW. Can always still land after the gear is retracted, but also gives you the option to climb if performance seems adequate. Just need to feather the prop and go, usually on normal take offs flaps are already up.

[Gino Under]

FWIW

Is it fair to say?
1) V1 is defined as the engine failure RECOGNITION speed.
2) V2 is defined as the MINIMUM SE flying speed.

If so, then...
The split can be significant between the two speeds. It's always nice to know what those two speeds are BEFORE you depart no matter what ME(L) aircraft you're flying. What you have to consider BEFORE any takeoff are the performance factors on the day in order to make the determination of those speeds. If you decide to make V1 your "go" speed, then V2 becomes your minimum safe flying speed to get you to the MSA and comply with the performance certification standards to at least 1500 feet AAE. When considering the environmental conditions at the time of your takeoff, it's wise to consider that the battle between V1 and achieving V2 could be a real struggle.
It is usually recommended (try not to think of it as mandatory) that a takeoff be discontinued should an engine fail at or below V1. There are always variables to consider. Not all takeoffs are the same nor do they necessarily happen on runways with the same declared distances and elevations. So remember, takeoffs will always give you a variation on what's considered normal so be aware that not all one-size-fits-all applies when making decisions. You could find yourself in a situation where "go" is the better decision. What then? The suspicion you should have is when an operator in its SOP tells you in all cases to discontinue a takeoff if an engine fails at V1. Such writings simply remove the reject decision from the PIC who will ultimately 'wear it' if it all turns to puppy mush. I can assure you, authors who write those kinds of SOPs will be nowhere to be found when it comes time to clean up the mess.

https://aviation-safety.net/database/re ... 19920730-0

I could keep my Navajo/King Air/CRJ/B777 on the runway beyond V1 if I decide to "go" with sufficient runway remaining, achieve V2 plus a few knots for the family, rotate, then use the initial climb to reduce my speed to V2 plus a safety factor for maneuvering (usually 10 knots).
I'd say, this is a general consensus based on the preceding posts from those much smarter than me.

An excellent presentation on aircraft performance (FAR Part 25) is provided by APG. Our regulations closely, if not exactly, adhere to the FAA's Part 25 requirements anyway.

https://www.youtube.com/watch?v=iEULv-3LCEo&t=24s

cheers,
Gino Under

[jakeandelwood]

This discussion is why Cessna designed the Skymaster. I've never flown one but I imagine as far as light twins go it performs fairly well on one engine, can anyone comment on that who has flown one?