Advisory Circular (AC)

Engine Ingestion Of Water/Slush Due To Runway Conditions

File No. 5009-6-525 AC No. 525-017
RDIMS No. 528477-V3 Issue No. 01
Issuing Branch Aircraft Certification Effective Date 2004-12-01

1.0 Introduction

1.1 Purpose
1.2 Guidance Applicability
1.3 Description of Changes
1.4 Termination

2.0 References

2.1 Reference Document
2.2 Cancelled Document

3.0 Background

4.0 Acceptable Means Of Compliance

5.0 Flight Manual

6.0 Headquarters Contact

1.0 Introduction

1.1 Purpose

The purpose of this Advisory Circular (AC) is to provide guidance material for an acceptable means, but not the only means for demonstrating compliance with the requirements of Chapter 525 of the Airworthiness Manual (AWM) dealing with the induction system.

1.2 Guidance Applicability

This document is applicable to all Transport Canada personnel, delegates and industry.

1.3 Description of Changes

This document, formerly AMA No. 525.1091, is reissued as an AC. With the exception of minor editorial changes the content is unaltered.

1.4 Termination

This document does not have a terminating action. It will however, be reviewed periodically for suitability of content.

2.0 References

2.1 Reference Document

It is intended that the following reference material be used in conjunction with this document:

Chapter 525 of the Airworthiness Manual (AWM) - Transport Category Aeroplanes.

2.2 Cancelled Document

As of the effective date of this document, AMA No. 525.1091 dated 1 May 1986 is cancelled.

3.0 Background

The need for more definitive and uniform test standards came into focus when an aircraft had engine surge problems during a runway water ingestion test. The existing regulation is adequate in recognizing the hazard of water or slush ingestion into engine inlets during takeoff or landing; but there is a lack of advisory material on acceptable means of compliance. Flight manual limitation of runway water depth was proposed but was rejected because it is unrealistic to expect aircrew to discriminate water depth below 13 mm (1/2 in) with sufficient accuracy to allow the use of such limitations. During an ensuing study it was found that FAA regulatory material does not contain specific test standards but JAR and BCAR specify 19mm (3/4 in) water depth and suggest trough dimensions in their advisory materials. 19 mm (3/4in) of standing water are considered to represent the worst condition, which may be encountered in Canada on an active runway. This advisory material provides criteria consistent with other foreign airworthiness agencies (CAA, DGAC).

4.0 Acceptable Means Of Compliance

Acceptable means to demonstrate compliance with paragraph 525.1091(d)(2) are the following:

(a) Trough:
 
(i) Length - The length of the trough shall be established to produce a stable wave/spray pattern and enough exposure time to evaluate effects on the engines. Usually, the length will be between 50m (164 ft) and 70m (230 ft).
 
(ii) Width - The width of the trough shall be such that a realistic wave/spray pattern can be established. If it can be shown that some of the wheels would not contribute to the overall amount of water entering the engine inlets in any configuration and speed considered, then the trough width may then be reduced appropriately.
 
(iii) Water Depth - The depth of water shall be at least 19mm (3/4 in) over 85% of trough area with no significant dry spots.
 
(b) Test Configuration - All configurations normally used during take-off or landing, must be tested including operation of spoilers, flaps and thrust reverser etc., which may affect water spray trajectories. Power settings should correspond to aircraft configuration, such as maximum take-off with take-off flap settings and idle power with landing flap. The aircraft tested must include optional equipment, which affects water spray pattern or engine intake. Such pressure), gravel kits, engine anti-ice equipment; etc.
 
(c) Speed Range - A sufficient range of test speeds, must be covered to enable a finding of compliance to be made, in the landing case, from max landing speed to thrust reverser cut-off speed, in the take-off case, up to maximum VR/VLOF taken from the AFM, and in the rejected take-off case, up to V1 max taken from the AFM.

5.0 Flight Manual

When an aircraft has successfully shown tolerance to the contaminated runway condition identified above, no limitations on water depth is required in the flight manual.

6.0 Headquarters Contact

For more information please contact:

Policy Standards Coordinator (AARDH/P)
Phone: (613) 990-3923
Facsimile: (613) 996-9178
E-mail: AARDH-P@tc.gc.ca

Original signed by Maher Khouzam

Maher Khouzam
Chief, Regulatory Standards
Aircraft Certification Branch

 

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