2StgTurbine

My current company has us retract the flaps at 400 ft AGL, yet looking at our single engine performance data, each runway has a specific acceleration height that is often much higher than that. The way it was explained to me is that we only need to use the single engine acceleration height if an engine fails at V1.

Beyond the CRM nightmare of ensuring we both remember to switch our minds from the two-engine acceleration height to the single engine acceleration height, since we only have performance information for a two-engine takeoff and a single engine takeoff, if we lost an engine after V1, but before the single engine acceleration height, we are in unknown territory. To me the solution is to just use the single engine acceleration height as our two engine acceleration height.

This would require a major redo of you SOPs, so before I propose it, what do you think? Am I missing a simpler solution? Is this even an issue?

2StgTurbine

Can a Mod correct the title to departures please.

Flyhayes

Our company has us retract the flaps at acceleration height.
I think this is the safer solution than having to completely reconfigure ones thinking in a an even higher workload situation.

Adlerdriver

This discussion is going to be a bit tough because there will be lots of perspectives depending on equipment, company OPSPECs, aircraft certification regulations and which regulations the companies are operating under.

First, what equipment are you operating? Second, part 91?, 121?, 135?



Third, could you clarify something before I get going on the wrong page:

Are you saying that someone told you that, for example, if you lost an engine after V1 at liftoff, 10 feet above the runway, you would use the normal flap retraction/accel altitude (for you) of 400' rather than whatever was published for the EO accel altitude?

2StgTurbine

Citation Excel part 135 and we use APG for performance data. And to answer your question they answer I was told is yes. In fact, the company I did my training at said if you retract the flaps above 400 feet, you are not flying the profile used for certification, so you would bust the checkride.

My personal understanding is, if you lose an engine between V1 and the normal acceleration altitude (400 ft for me), continue the second segment climb (flaps in T/O) until the level off altitude indicated received from APG.

What to do if the engine fails between 400 ft and the OEI level off altitude, I can't find any reference for. Some people say you have enough energy at that point to zoom climb to the right level off altitude, but I like so paperwork to CYA if that ever happened. Sure, and engine failure at 1,000 ft AGL is probably no big deal, but an engine failure at 500 ft with a 2,000 ft level off altitude seems like a big gap.

cougar

In regard to all engine acceleration height, turbojet aircraft generally have to comply with NADP 1 or NADP 2 departure procedures. Some airports specify which is required, either for near or far noise sensitive areas. These departure procedures are found in AC 91-53A, JAR-OPS 1.235 or PANS OPS Vol 1 Doc 8168.

NADP 1 (Near) requires a thrust reduction at or above 800' and climb at V2 +20 until no more than 3000' accelerate and retract flaps.

NADP 2 (far) accelerates at or above 800', and reduces thrust at or after flap retraction.

It is surprising that your SOPs call for flap retraction at 400'. The regs quoted above apply to part 135, but not familiar with your aircraft certification requirements.

Engine inoperative performance is valid for the engine failure at or after V1. If the engine failure were to occur after rotation or liftoff, your performance will be slightly better than if the EF occurred at V1 due to the benefit of all engine acceleration and climb until the EF.

2nd segment climb starts at gear retraction to a minimum of 400'. Most operators use an EO accel height greater than 400' (800 or 1000, etc) due to net and gross flight path and obstacle clearance.

Many operators have their standard EO accel height and the all engine accel height the same (Our fleet uses 1000'). However, for obstacles in 2nd or third segment climb, the EO accel altitude will be higher.

jonnyjetprop

Here's a great video from our friends at the FAA: https://m.youtube.com/watch?v=vy_nn_DwcxQ

Adlerdriver

Quote:

Originally Posted by 2StgTurbine

Citation Excel part 135 and we use APG for performance data. And to answer your question they answer I was told is yes. In fact, the company I did my training at said if you retract the flaps above 400 feet(in which scenario? – normal or engine failure), you are not flying the profile used for certification, so you would bust the checkride.

I’m sorry – I’m still not following your answer. Do you mean they said you must always accelerate and retract the flaps at 400 feet even if you lose an engine and there is a higher EO acceleration altitude?
If so, perhaps they are talking about a max performance takeoff situation where you are right up against the Part 25 certification limits of the aircraft which only require an engine out climb to 400 feet before clean up.

Quote:

Originally Posted by 2StgTurbine

My personal understanding is, if you lose an engine between V1 and the normal acceleration altitude (400 ft for me), continue the second segment climb (flaps in T/O) until the level off altitude indicated received from APG.

This makes sense to me. If you could do it from V1 on the runway (worse case), you can do it from any point between then and then end of second segment. However, that assumes you're using aircraft and runway specific performance calculations.

Quote:

Originally Posted by 2StgTurbine

What to do if the engine fails between 400 ft and the OEI level off altitude, I can't find any reference for. Some people say you have enough energy at that point to zoom climb to the right level off altitude, but I like so paperwork to CYA if that ever happened. Sure, and engine failure at 1,000 ft AGL is probably no big deal, but an engine failure at 500 ft with a 2,000 ft level off altitude seems like a big gap.

If it fails after 400 feet, you have started the 3rd segment and are accelerating and retracting flaps. Your climb performance is going to be significantly better clean and fast than at V2 with flaps extended. I would think that the best option would be to continue the acceleration/clean-up process and then climb rather than stay slow.

It may be that a particular aircraft’s performance limits on a particular takeoff bump right up against the certification limits and it does not have the excess performance to hack obstacles/terrain clearance requirements. Usually those are the situations that involve use of an engine failure departure procedure which will provided a safer ground track that allows better clearance.

Adlerdriver

Quote:

Originally Posted by cougar

In regard to all engine acceleration height, turbojet aircraft generally have to comply with NADP 1 or NADP 2 departure procedures. Some airports specify which is required, either for near or far noise sensitive areas. These departure procedures are found in AC 91-53A, JAR-OPS 1.235 or PANS OPS Vol 1 Doc 8168.

NADP 1 (Near) requires a thrust reduction at or above 800' and climb at V2 +20 until no more than 3000' accelerate and retract flaps.

NADP 2 (far) accelerates at or above 800', and reduces thrust at or after flap retraction.

It is surprising that your SOPs call for flap retraction at 400'. The regs quoted above apply to part 135, but not familiar with your aircraft certification requirements.

Those NADP procedures normally apply to aircraft operating over 75,000 lbs. TOGW. His aircraft isn’t in that category. Noise abatement procedures have no correlation with aircraft certification requirements and there are some aircraft out there that simply cannot comply with the profiles you listed.

Quote:

Originally Posted by cougar

2nd segment climb starts at gear retraction to a minimum of 400'. Most operators use an EO accel height greater than 400' (800 or 1000, etc) due to net and gross flight path and obstacle clearance.

Many operators have their standard EO accel height and the all engine accel height the same (Our fleet uses 1000'). However, for obstacles in 2nd or third segment climb, the EO accel altitude will be higher.

That works fine if the aircraft has the EO performance to allow a higher acceleration altitude or the convenience of matching normal and EO acceleration altitudes in their procedures. That level of performance is usually attainable with most large transport category aircraft these days.

One part of the equation that can be a factor is the engine time limit at takeoff power. Certification limits on an engine out takeoff require that the power cannot be reduced to MCT until the aircraft is clean. I believe the minimum certification limit for jet engines at T/O power is 5 minutes. A performance limited aircraft may not have the luxury of a climb above 400 feet before accelerating and retracting flaps. To do so might require several additional minutes at T/O power and exceed that engine operating limit.

jonnyjetprop

The big issue is making sure the profile matches the data you're using. My jet and my data can use anything from 400 to 1500 ft. The key is that they match. If your data provider uses a 400 ft. level off, then use 400 ft.

For what's it's worth, the MD-80 is authorized (with special training and FAA authorization) to use max thrust for up to 10 minutes. It's required when the level off altitude is lower, not higher. No matter what the level off, runway analysis ends at 1500 ft. AGL.