Advisory Circular (AC)

Flight In Icing Conditions - Flight Characteristics

File No. 5009-6-525 AC No. 525-007
RDIMS No. 528426-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 Documents
2.2 Cancelled Document

3.0 Background

4.0 Procedures

5.0 Headquarters Contact

1.0 Introduction

1.1 Purpose

The purpose of this Advisory Circular (AC) is to provide guidance material for acceptable means, but not the only means, of demonstrating compliance with the flight characteristics requirements of Chapter 525 for the approval of Transport Category Aeroplanes for flight in icing conditions.

This advisory material is presently the subject of international harmonisation, and this AC is issued for use during type approval programs. When harmonisation is completed, this AC will be amended, or revoked and the corresponding harmonised advisory material adopted.

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. 525/5A 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. Not applicable.

2.0 References

2.1 Reference Documents

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

(a) Chapter 525 of the Airworthiness Manual (AWM) - Transport Category Aeroplanes;
 
(b) Transport Canada Advisory Circular (AC) 525-004 - Flight in Icing Conditions; and
 
(c) Federal Aviation Administration Advisory Circular (FAA AC) 20-73 - Aircraft Ice Protection.

2.2 Cancelled Document

As of the effective date of this document, AMA No. 525/5A dated 20 October 1999 is cancelled.

3.0 Background

The equipment design requirements for ice protection are contained in Chapter 525, Sections 525.1093, 525.1416 and 525.1419. FAA Advisory Circular 20-73 contains information relating to substantiation of ice protection systems and AC 525-004 provides additional advisory information for Performance aspects of flight in icing conditions. This AC provides additional advisory information for the Flight Characteristics aspects of flight in icing conditions.

4.0 Procedures

(a) In general, flight in icing conditions can include take-off and climb, cruise, descent and landing. During the take-off phase it may be assumed that there is negligible ice accumulation, but operation of the ice protection systems has to be considered. For the other flight phases it should be assumed that operation of the ice protection systems is required. Approval of flight in icing conditions requires compliance with the following requirements:
 
(i) Flight characteristics with ice accumulations appropriate to 45 min in Chapter 525 Appendix C conditions (3 inch maximum) on the unprotected surfaces and normally expected ice on the protected surfaces prior to anti-icing system activation or during de-icing system operation.
 
(ii) Demonstration of freedom from hazardous flight characteristics with ice accumulation resulting from probable single failure conditions or probable delays in crew operating procedures. For failure conditions which require that the aircraft leave the icing conditions as soon as possible, the ice accumulation may be assured to be one half of the accumulation specified in (a)(i) above.
 
(iii) Adequate Aircraft Flight Manual (AFM) procedures including procedures for anti-icing and de-icing system failure conditions.
 
(b) The following items have been found to be significant in past certification programs. It is recognised that for a particular aircraft the list may not be complete.
 
(i) Demonstration of adequate stall warning.
 
(ii) Demonstration of satisfactory stall characteristics.
 
(iii) Demonstration of adequate stability and control in the Control capability and positive Static Lateral/Directional Stability, Static Longitudinal Stability and Dynamic Stability at VAPP to VFE.
 
(iv) Demonstration of safe procedures for configuration flap at VAPP to VFE.
 
(v) Demonstration of adequate Static Longitudinal Stability and Dynamic Stability in the cruise configuration.
 
(vi) Demonstration of freedom from vibration and buffet with de-icer boot operation at speeds up to VFC.
 
(vii) Demonstration of no adverse fluctuations of altitude or airspeed (e.g. caused by ice build-up on nose radome).
 
(viii) Demonstration of no hazard associated with ice shedding (e.g. from propellers, under wing de-icer boots, lights).
 
(ix) Establishment of adequate AFM procedures for anti-icing and de-icing systems operation. (e.g. minimum "N1" for adequate bleed air supply).
 
(x) Establishment of adequate AFM procedures for anti-icing or de-icing system failures or other applicable failures (e.g. engine failure). Tests should be carried out in simulated failure conditions to ensure no hazardous characteristics exist.
 
(xi) Establishment of any systems limitations/procedures when operating in icing conditions (e.g. autopilot must be disengaged).

5.0 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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