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inbalance
18th May 2008, 23:49
Hi folks,

can anybody tell me where it is written that you have to calculate landing distance without reverse ? FAR 23 Turboprop, JAR country.


thanks

Inbalance

roljoe
19th May 2008, 16:45
Hi,

just to mention that for a jet (not familiar with turboptos) the reverse are never taken into consideration during the certification process, and all computed perfo...perfo that will be used trhough the afm for operationnal calculations..

rgds

mutt
19th May 2008, 18:37
the reverse are never taken into consideration during the certification process,

What about for wet/contaminated performance??

Mutt

inbalance
19th May 2008, 20:29
just to mention that for a jet (not familiar with turboptos) the reverse are never taken into consideration during the certification process, and all computed perfo...perfo that will be used trhough the afm for operationnal calculations..


That doesnīt help me. Because everybody tells me that, but nobody can prove it for FAR 23 Aircraft. I have asked Examiners, Flightinstructors and a lot more People, and they all told me that you canīt use the reverser for calculation.
But when I asked them where to find the Law, they all replied I donīt know, some guy told me years ago.
It isnīt in JAR-OPS, not in national Law and not in the POH of our Aircraft.
So where can I find it in written form?

Thats what FAR 23 says about braking:

(f) Retardation means other than wheelbrakes may be used if that means -

(1) Is safe and reliable;

(2) Is used so that consistent results can be expected in service; and

(g) If any device is used that depends on the operation of any engine, and the landing distance would be increased when a landing is made with that engine inoperative, the landing distance must be determined with that engine inoperative unless the use of other compensating means will result in a landing distance not more than that with each engine operating.



Maybe someone can correct me:
According to FAR 23, when I make a single engine Landing, I have to calculate without the reverser. That means I have to divert if the destination isnīt long enough. But for a normal landing with both engines operative, I can calculate including reverse.


Inbalance

SNS3Guppy
19th May 2008, 20:35
Part 23 aircraft which have reverse generally provide charts for stopping with and without reverse or correction factors for it's use. Part 25 aircraft don't use reverse as part of the stopping equation.

If you're in a Part 23 airplane, how you use what's available to you is up to you.

Personally, I'd calculate it without reverse. You'll have only an advantage to contend with when it's available, and nothing to lose if it's not. If you plan to have reverse and then it's not available, you're plum out of luck.

ssg
19th May 2008, 20:36
That's incorrect...TRS like reverse props are generaly not calculated into braking distances..

inbalance
19th May 2008, 20:41
That's incorrect...TRS like reverse props are generaly not calculated into braking distances.

is written where ?????


Inbalance

inbalance
19th May 2008, 20:44
Part 23 aircraft which have reverse generally provide charts for stopping with and without reverse or correction factors for it's use. Part 25 aircraft don't use reverse as part of the stopping equation.

If you're in a Part 23 airplane, how you use what's available to you is up to you.

Personally, I'd calculate it without reverse. You'll have only an advantage to contend with when it's available, and nothing to lose if it's not. If you plan to have reverse and then it's not available, you're plum out of luck.


Yes, that is what I believe. We do have performance charts including the help of reverser. But when I am going to calculate with that, I want to be shure that it is legal under JAR-OPS.

Inbalance

SNS3Guppy
19th May 2008, 20:56
Why would you calculate takeoff or landing performance with reverse?

Calculate without it. Are you looking for a justification or reason to use reverse in your calculations?

What will you do when it's not available?

ssg
19th May 2008, 21:17
You could listen to the sim instructors, the examiners, and me...

Or you could go to my Citation manual. which states that TRs weren't included in the landing data.....and probably your flight manual as well, and might talk about how the breaking distances were derived..

Your aircraft could be different...and how it was certified could be different...maybe working reverse is required on that aircraft...you didn't state which type..

The theory is that braking technique is pretty standard, levers back, apply brakes...but trying to define how much one pilot adds in TRs and revers prop is harder to quantify when it comes to hard landing distances. With reverse props...going from a McCualy 4 blade to a three blade, changes things..but the book numbers stay the same....And also many models of Citations and Lears for instance didn't have TRs, then aftermarket ones came out...they ddin't recertify landing distances with TRs added..

I mean some Lears had parachutes...anyone got any landing distance numbers with a parachute vs without (As I open up my lear book)

This conversation could follow to adnauseam where brake mods, Vortex Generators, Ram engine upgrades, ect installed on the aircraft are there to help but many times you don't get a piece of paper that says you can fly faster, heaver, land shorter ect....

Guppy...you may have hit something there..he may be trying to get into a field that is shorter then his landing distances allow by using his reverse...

inbalance
19th May 2008, 21:24
My aircraft has a landingdistance of 3000 ft without propeller reversing
and 2500 ft with propeller reversing.

Operated under JAR-OPS 1, I need 3000 ft x 1.42 = 4260 ft without reversing
and 2500 ft x 1.42 = 3550 ft with propeller reversing.

So if I could calculate with reversers, I could land at 710 ft shorter Airfields.

The Landing distance without reversers and without the JAR-OPS Factor (3000ft) is shorter than the required distance with reversers and including the factor 1.42 (3550ft)


So it is still save even when the reversers will fail.


Inbalance

SNS3Guppy
19th May 2008, 21:37
That's convoluted logic. Count on having no reverse. You may end up flying that approach single engine with limited assymetrical reversing capability. You may find it's a wet runway or icy runway with definite assymetrical reversing capability. You may find you only get one engine into reverse. You may find that reverse isn't available at all. If you plan for th elandin gwithout reverse, you're best off. Don't count on something that may not be there. Same way we plan for takeoffs with an engine failure. Don't count on reverse being available for a rejected takeoff, and never count on it for landing.

ssg
19th May 2008, 21:39
Imbalance...if you were a little more upfront at the beginning ..

Ok. So what your saying is...'can I get away with getting into a field using reverse because the non reverse numbers won't make it...in a foreign country'...Probably France right? Your worried your going to get nicked after landing by the authorities and want to hand them a piece of paper and a middle finger! Why didn't ya say so!

The fact that you HAVE a plane certified with braking distances to include reversers is your 'piece of paper' ...if that distance says you can make it in, then your golden..

Secondly, I don't think any country has in thier regs a requirement telling you how to land a plane, with reverse or not..

inbalance
19th May 2008, 23:18
SSG,

So what your saying is...'can I get away with getting into a field using reverse because the non reverse numbers won't make it...in a foreign country'.

Yes, thatīs exactly what I wanted to say.

I have to apologise that I didnīt make it that clear. I am ICAO english 4 only, if that counts. ;)


So you think I can do it that way, as long as I take into acount that the reversers could fail and I still can stop the aircraft with brakes only.

I donīt want to show anybody a finger. My plan is to get a thumbs up for that from our authorities in advance. But before that I want to make shure, that I havenīt overread something.
I studied the related Papers for 3 Month now and I couldnīt find anything against it. So I started to talk to more experienced people, but all they had to say was that I canīt use the reversers for planing.

Nobody could tell me where it is written, but they all where shure that it is prohibited. All I could find is an old german law, the LuftBO. The LuftBO sayed that you canīt use reversers. But the LuftBO was replaced by JAR-OPS.
I think they all havenīt recognized that this old Law is no longer valid and even Instrucors still teaching it the old way.
FAR 25 might be different, but there are still a lot of FAR 23 aircraft still in production.

Inbalance

SNS3Guppy
19th May 2008, 23:22
The operating rules are really irrelevant. Consider the practical wisdom of restricting yourself to planning to not have reverse available. I understand completely what you're saying, and any time you have to justify something by saying "what can I get away with," you're in error.

Time to check yourself.

You may legally proceed and plan for the use of reverse. If you're wise, you'll plan for landing without it, and take any reduction in landing distance you actually achieve with reverse, as a bonus.

ssg
20th May 2008, 00:50
Imbalance...sounds like your legal to me.

If you know what your doing, and know your equipment well, getting into strips that no one else can is really fun.. No doubt your upping the risk by needing reversers for the landing vs just brakes, but a super low approach speed, ref -10 - 15, flat approach...short field techniques....

Keep in mind, there are short field pilots and there are those that admonish the practice...the doers and the watchers....

As far as advice in here...there are guys that won't do that flight, calling it unsafe, then fly thier airliner to the fence overgross, on reduced power,...take it all with a grain of salt...

Give me a call, I'll fly with ya!

inbalance
20th May 2008, 01:19
My english isnīt the best.

but numbers, I think are the same in all langages.

The operating rules are really irrelevant. Consider the practical wisdom of restricting yourself to planning to not have reverse available. I understand completely what you're saying, and any time you have to justify something by saying "what can I get away with," you're in error.

Time to check yourself.

You may legally proceed and plan for the use of reverse. If you're wise, you'll plan for landing without it, and take any reduction in landing distance you actually achieve with reverse, as a bonus.

SNS3Guppy, did you read my post ??

My airplane can land without reverse on 3000 ft runways.
But I canīt land at a 3000 ft runway without reverse, because JAR-OPS asks to add 42 % safety margin.
So to be legal the runway has to be 4260 ft long. The aditional 1260 ft are for the worst case.

What I am planing to do is:

My airplane can land at 2500 ft with the use of reversers.
To be legal according to JAR-OPS I need to add 42% to that as well.
That makes 3550 ft Runway available to plan legaly acording JAR-OPS with reversers.

So the runway will be 3550 ft long.(planning with reversers)
My plane can stop at 3000 ft without reverse.
So when the reverser donīt work, I will come to a stop after 3000 ft.
550 ft runway left in front of me.

And all this is calculated overflying the treashold at 50 ft.
Normaly the treashold is the place where I touch down.

Now tell me, why do I have to check myself ?


Inbalance

mutt
20th May 2008, 13:19
Inbalance,

What manual are you getting the performance figures from? Airplane Flight Manual or Airplane Operations Manual?

As per the FAR:
(f) Retardation means other than wheelbrakes may be used if that means -

(1) Is safe and reliable;

(2) Is used so that consistent results can be expected in service;

This basically means that if the aircraft want to certify the aircraft with the use of thrust reverse as a stopping means, they have to prove its reliability. Its quite possible that your aircraft manufacturer certified the use, if so, the figures will be in the AFM, if they are in the AOM, they arent certified figures. You will have a much easier time convincing the authorities if the data is in the AFM.

Mutt

Denti
20th May 2008, 13:44
First of all JAR OPS 1 is only applicable if you are flying under an AOC, Werksverkehr is not covered by that. Second, you can get excemptions from the factoring required by JAR OPS 1, but you have to apply on a case by case basis to the LBA. We did it for our premier into Albenga and got an approval, however for private flights (of the owner) only.

Best of all just ask the LBA and give them all the relevant information, they are cooperative if you are as well.

OutOfRunWay
20th May 2008, 14:43
Those added 42% runway length are there for when things go pear-shaped.
Imagine a slightly damp runway, where there are rubber smears remaining on the first third of the RW from people braking hard (not unusual on short runways). Now you will suddenly find your braking action is all but gone. Then use full reverse and with a little crosswind, you may wander off into the grass.

Never base your numbers so that it will barely work when everything goes right. Aviation history is littered with bodies who relied on nothing going wrong.

Regards, OORW

inbalance
22nd May 2008, 10:38
Those added 42% runway length are there for when things go pear-shaped.
Imagine a slightly damp runway, where there are rubber smears remaining on the first third of the RW from people braking hard (not unusual on short runways). Now you will suddenly find your braking action is all but gone. Then use full reverse and with a little crosswind, you may wander off into the grass.

Never base your numbers so that it will barely work when everything goes right. Aviation history is littered with bodies who relied on nothing going wrong.


OOR: I know what you want me to say.

I shall calculate for the worst case.

So whats the worst case? No reverser and no brakes !!!!
I donīt have a Graph for that in the books, so what?
Guess it? I think I would need about 6000 or maybe 7000 ft Runway with both US.

Shall I plan into 7000 ft Runways only ??


No, thats not what I am going to do.

I fly FAR 23 Aircraft comercial since 1992. Since 1995 as a Captain. We are opreating under JAR-OPS 1.
I donīt need somebody to tread me like a schoolboy telling me that the runway may slippery.
I told you, that I can stop without reversers within 3000 ft.
With reversers working it will be 2500 ft only.
The runway I am planning to land at, has to be 3550 ft long.
So plenty of reserve for me.

The next thing is, all the landing data is based on overflying the treashold at 50 ft.
All this small airfields are VFR. I donīt follow a GS there, wich will bring me just 50 ft over the treashold, leaving 1000 ft of good runway behind me when I touch down. Without this 50 ft, touching at the threashold, I need 1700 ft landingdistance only, with brakes and reversing.
No Rubber of hard braking pilots at the treashold, because they all overflying at 50 ft.
Pilots touching at the beginning of the runway donīt need to brake hard. ;)

I know, that planning my aircraft with reversers and JAR-OPS 1 additionals are safe for me.
AND I KNOW I HAVE TO ADD ANOTHER 15% IF THE RUNWAY IS WET.
All I was asking here is:

Can I legaly do it, or is there any law against it.


regards

Inbalance

OutOfRunWay
22nd May 2008, 12:48
My apologies, inbalance.

I've just noticed on rereading the entire thread that I missed your initial post and did not understand the original issue.

In answer to your original question - I cant find it either, but I think I know who to ask. I may be back with an answer.

Regards, OORW

mutt
22nd May 2008, 15:46
If the data is in the AFM, you can do it without question, if its in the AOM, you can approach your authorities and seek permission.

Mutt

411A
22nd May 2008, 15:52
The next thing is, all the landing data is based on overflying the treashold at 50 ft.
All this small airfields are VFR. I donīt follow a GS there, wich will bring me just 50 ft over the treashold, leaving 1000 ft of good runway behind me when I touch down. Without this 50 ft, touching at the threashold, I need 1700 ft landingdistance only, with brakes and reversing.


This might work for your small FAR23 aeroplane, imbalance, but will most definitely not work for larger jets, for when this 'duck-under' is tried with many jet transports, the main landing gear may well become entangled in the approach lights frangible bits, with expensive results.

In any case, the 'duck-under' maneuver has been the cause of several accidents, especially when unpredictable windshear may be present.

I don't suppose that my remarks will be especially appreciated, however, by a few of the more younger pilots, who may well consider themselves ace-of-the-base....for sooner or later, their luck will run out.

Angels 60
22nd May 2008, 18:31
Imbalance..sorry you have to take comments from anonymous posters questioning your judgement and ability...

Just call the JAA people...give them your SIT REP...

SNS3Guppy
22nd May 2008, 19:02
For those following along, bear in mind that Angels 60 is the same poster who got the boot as ssg, and Trickle451.

yrvld
23rd May 2008, 09:27
Try JAR–OPS 1.515 Landing – Dry Runways and following.
Also see if you find anything in AMC OPS 1.510 and 1.515 or search "performance class" in the JAR OPS.

DFC
23rd May 2008, 10:00
(g) If any device is used that depends on the operation of any engine, and the landing distance would be increased when a landing is made with that engine inoperative, the landing distance must be determined with that engine inoperative unless the use of other compensating means will result in a landing distance not more than that with each engine operating.



I believe that the answer is in the above from post 4.

Reverse depends on the operation of that engine. Without that engine and it's reverse, landing distances will be increased.

How much reverse can you have on the operating engine with the other feathered? If anything it will be limited.

Thus reverse available from both engines is affected by the failure of any one engine.

So you can not use the reverse to claculate the required distances because it "depends on the operation of any engine".

I expect that your aircraft does not have something else to compensate for the loss of revese so unless the certification people have managed to get the figures with reverse approved for normal dry ops and thus in the flight manual, you are stuck with the figures as published.

-------

Just to correct one small point made earlier - the 1.42 factor does not give a 42% safety net.

A 1.42 factor means that you will stop within 70% of the runway leaving 30% of the runway available as a safety net.

Regards,

DFC

Angels 60
23rd May 2008, 17:47
DFC....I never thought of it that way!..excellent post...yes under single engine ops, reverse on on the bad engine wouldn't be available...how obvious that reverse wouldn't be calculated into landing distances for that reason on many aircraft.

Evidentely, in Imbalance's he has reverse numbers...no plane I ever flew did...nice to have if you need them.

Thanks!

bobrun
25th May 2008, 08:21
Here's what I thought....

With no failures, reversers are never taken into considerations when calculating distances. However, with a failure and a wet/contaminated rwy, then reversers must be considered in the distances.

Sounds like some are trying to push the limits a little by reducing the landing distance calculations by all means...perf calculations have evolved from the industry's experience and accidents/incidents records...why not use that wisdom and stick to well accepted policies on how to calculate distances? Even if you find a piece of law that allows you to use reversers in all calculations, it won't really help you once you're in the dirt at the far end of the rwy!