max depth of contaminant

[gigi116]

On the JAA approved AFM supplement for wet / contaminated RWYs (Hawker 800XP) there are no published information/limitation regarding the max depth of contaminant allowed on take off and landing.

A max scale value of 0.5 inch is published on landing graphs (except for Compacted snow) therefore I " imagine " 0.5 inch may be considered as limitation for landing - but nothing for take off is published-

My questions are :

1) Considering no limitations are published, may I take off with 2 inches of contaminant ?

2) Is there any other applicable regulation ?

thanks

[Daysleeper]

nothing for take off is published-

Then public transport normally you cannot operate! Private ops you may compromise your insurance by operating outside your AFM... you sure you've not misplaced a page or two?

It is normal that you cannot extrapolate from the numbers in a set of performance tables. Therefore if the deepest contaminant for which you have published performance is 0.5 then that is your limit.

There is no requirement in current certification (cs-25) to produce figures for contaminated operations... it is simply a case that if those figures are not supplied then operation is prohibited and the AFM should say so. Not sure if that was the case when the 800XP was certified but it makes sense.

[gigi116]

Apologize my previous question was not very clear

AFM supplement has tables for take off and graphs for landing, both for any type of approved contaminant (except ice and wet ice which are not approved).

While in the landing graphs the depth of contaminant is taken in consideration (I agree daysleeper that max value shown may be considered as the limits) , all take off tables has no indication for depth .

I need to know the max depth of contaminant I can accept on take off for each type on contamination.

I have found on the web some informations from Boeing / Airbus which, I suppose, do not apply to my airplane as related to type of wheels, distance from engines etc etc (they accept dry snow up to 60 mm. ! ).

Nothing found from Aviation Authorities related to contaminant depth , except FAA which has guidance material (but very very old).

Thanks again and happy new year !!!!

[safetypee]

Where an EU operator is approved to operate in contaminated conditions suitable (approved) data must be provided. One means of compliance is given in CS-25, AMC 25.1591. This requires an explanation of the basis of the data, its limits, and the assumptions in use, to be included in the AFM.
The range of contaminants, including depths to be considered, are given in para 5.

The CS 25 information should apply to an older JAA approval as the new CS-25 AMC is based on draft JAA proposals (NPA) for calculating contaminated data.
Note the general assumptions in CS-25 AMC 25.1591 and caveats about data calculation; whether reverse thrust use is assumed or not, the relative risks compared with normal operations, and procedures to be used.

para 8.1.1
Operation on runways contaminated with water, slush, snow, ice or other contaminants implies uncertainties with regard to runway friction and contaminant drag and therefore to the achievable performance and control of the aeroplane during take-off, since the actual conditions may not completely match the assumptions on which the performance information is based. Where possible, every effort should be made to ensure that the runway surface is cleared of any significant contamination.

[gigi116]

......finally I have found in the AFM Supplement some graphs for the correction of the TOFL from tables including the deepth of contaminant. (Max value is 0,5 inch for any contaminant). Also downloaded CS25 .

Thanks to all of you !

[Sir George Cayley]

Is the 0.5 an absolute depth of contaminant or equivalent water depth?

Sir George Cayley

[mutt]

The 1/2 inch limitation applies to a lot of aircraft to avoid impingement damage.

Mutt