AD/Y12/8 - Aircraft Flight Manual, Flight into Icing Conditions

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AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

 

Harbin Y12 Series Aeroplanes

 

AD/Y12/8 Aircraft Flight Manual, Flight into Icing Conditions 3/2003

 

Applicability: All Y12II aeroplanes.

 

Requirement: 1. Revise the CAAC and FAA approved Airplane Flight Manual (AFM) by incorporating the following into the Limitations Section of the AFM:

 

“Except for certain phases of flight where the AFM specifies that de-icing boots should not be used (e.g. take-off, final approach, and landing), compliance with the following is required.

 

  1. Wing and Tail Leading Edge Pneumatic De-icing Boot System, if installed, must be activated:

 

  1. At the first sign of ice formation anywhere on the aircraft, or upon annunciation from an ice detector system, whichever occurs first; and

 

ii.        The system must either be continued to be operated in the automatic cycling mode, if available; or the system must be manually cycled as needed to minimize the ice accretion on the airframe.

 

b.        The wing and tail leading edge pneumatic de-icing boot system may be deactivated only after leaving icing conditions and after the airplane is determined to be clear of ice.”

 

2.        Revise the CAAC and FAA approved Airplane Flight Manual (AFM) by incorporating the following into the Limitations Section of the AFM:

 

“WARNING

 

Severe icing may result from environmental conditions outside of those for which the airplane is certificated. Flight in freezing drizzle, or mixed icing conditions (supercooled liquid water and ice crystals) may result in ice build-up on protected surfaces exceeding the capability of the ice protection system, or may result in ice forming aft of the protected surfaces. This ice may not be shed using the ice protection systems, and may seriously degrade the performance and controllability of the airplane.

 

Harbin Y12 Series Aeroplanes

 

AD/Y12/8 (Continued)

 

During flight, severe icing conditions that exceed those for which the airplane is certificated shall be determined by the following visual cues. If one or more of these visual cues exists, immediately request priority handling from Air Traffic Control (ATC) to facilitate a route or an altitude change to exit the icing conditions:

 

  1. Unusually extensive ice accumulation on the airframe and windshield in areas not normally observed to collect ice.

 

b.        Accumulation of ice on the lower surface of the wing aft of the protected area.

 

c.         Accumulation of ice on the engine nacelles and propeller spinners farther aft than normally observed.

 

Since the autopilot, when installed and operating, may mask tactile cues that indicate adverse changes in handling characteristics, use of the autopilot is prohibited when any of the visual cues specified above exist, or when unusual lateral trim requirements or autopilot trim warnings are encountered while the airplane is in icing conditions.

 

All wing icing inspection lights must be operative prior to flight into known or forecast icing conditions at night. (NOTE: This supersedes any relief provided by the Master Minimum Equipment List).”

 

3.        Revise the CAAC and FAA-approved AFM by incorporating the following into the Normal Procedures Section of the AFM:

 

“THE FOLLOWING WEATHER CONDITIONS MAY BE CONDUCIVE TO SEVERE IN FLIGHT ICING

 

  1. Visible rain at temperatures below 0 degrees Celsius ambient air temperature.

 

b.        Droplets that splash or splatter on impact at temperature below 0 degrees Celsius ambient air temperature.

 

PROCEDURES FOR EXITING THE SEVERE ICING ENVIRONMENT:

 

These procedures are applicable to all flight phases from takeoff to landing.

 

Harbin Y12 Series Aeroplanes

 

AD/Y12/8 (Continued)

 

Monitor the ambient air temperature. While severe icing may form at temperature as cold as -18 degrees Celsius, increased vigilance is warranted at temperatures around freezing with visible moisture present. If the visual cues specified in the Limitations Section of the AFM for identifying severe icing conditions are observed, accomplish the following:

 

  1. Immediately request priority handling from Air Traffic Control to facilitate a route or altitude change to exit the severe icing conditions in order to avoid extended exposure to flight conditions more severe than those for which this airplane has been certificated.

 

b.        Avoid abrupt and excessive manoeuvring that may exacerbate control difficulties.

 

c.         Do not engage the autopilot.

 

d.        If the autopilot is engaged, hold the control wheel firmly and disengage the autopilot.

 

e.         If an unusual roll response or uncommanded roll control movement is observed, reduce the angle-of-attack.

 

f.          Do not extend flaps when holding in icing conditions. Operation with flaps extended can result in a reduced wing angle-of-attack, with the possibility of ice forming on the lower surface further aft on the wing than normal, possibly aft of the protected area.

 

g.        If the flaps are extended, do not retract them until the airframe is clear of ice.

 

h.    Report these weather conditions to Air Traffic Control.”

 

Note 1: China AD CAD2000-Y012-02 Amdt 39-2824 refers.

 

Note 2: Operators should initiate action to notify and ensure that flight crew members are aware of the change.

 

Note 3: A copy of this Directive maybe inserted in the AFM to accomplish the amendment to the AFM.

 

Compliance: Unless previously accomplished, within 20 days of the effective date of this Directive.

 

This Airworthiness Directive becomes effective on 20 March 2003.

 

Harbin Y12 Series Aeroplanes

 

AD/Y12/8 (Continued)

 

Background:  This Directive is issued to minimise the potential hazards associated with operating the aircraft in severe icing conditions by providing more clearly defined procedures and limitations associated with such conditions.


 

James Coyne

Delegate of the Civil Aviation Safety Authority 3 February 2003

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


The above AD is notified in the Commonwealth of Australia Gazette on 26 February 2003.

Overview

The Airworthiness Directive (AD) for Harbin Y12 Series Aeroplanes, issued under the Civil Aviation Act 1988, was enacted in 2003 to address the potential hazards associated with operating these aircraft in severe icing conditions. The AD, identified as AD/Y12/8, was introduced to ensure the safety of flights by providing clearer procedures and limitations for operating in such conditions. The Civil Aviation Safety Authority (CASA), as the delegate of the Civil Aviation Safety Authority, issued this directive to correct an unsafe condition. The policy objective of this AD is to minimise risks to flight safety by updating the Airplane Flight Manual (AFM) with specific procedures for flight into icing conditions, ensuring that pilots are fully aware of the necessary actions to take when encountering severe icing conditions, thereby enhancing the overall safety and airworthiness of the aircraft in such environments.

Scope and Application

The Airworthiness Directive (AD) issued under subregulation 39.1(1) of the Civil Aviation Regulations 1998 applies to all Y12II aeroplanes, mandating specific amendments to the Airplane Flight Manual (AFM) to address severe icing conditions. The directive requires the incorporation of detailed operational procedures and limitations to manage flight into icing conditions, particularly focusing on the activation and deactivation of the wing and tail leading edge pneumatic de-icing boot system. This applies to all phases of flight except those explicitly stated in the AFM where de-icing boots should not be used. The directive also includes instructions to be vigilant for visual cues indicating severe icing, to request priority handling from Air Traffic Control to avoid such conditions, and to avoid using the autopilot in these situations. The AD mandates that these changes be implemented within 20 days of its effective date, which was 20 March 2003. This legislation extends its jurisdictional reach across the Commonwealth of Australia, ensuring compliance through subordinate instruments and notifications in the Commonwealth of Australia Gazette.

Key Provisions

The Airworthiness Directive AD/Y12/8 applies to all Harbin Y12 Series aeroplanes. It mandates revisions to the approved Airplane Flight Manual (AFM) to include specific guidelines on the use of de-icing boots and procedures for handling severe icing conditions. Firstly, under section 1, the AFM must state that the wing and tail leading edge pneumatic de-icing boot system must be activated at the first sign of ice formation or upon an ice detector system annunciation and must remain operational until the aircraft is clear of icing conditions. Secondly, under section 2, the AFM must warn against flying in conditions that exceed those for which the aeroplane is certificated, detailing visual cues that indicate severe icing conditions and advising immediate action to change routes or altitude. Section 3 further specifies normal procedures for exiting severe icing environments, including avoiding abrupt maneuvers and not engaging or disengaging the autopilot as necessary. These changes must be made within 20 days of the Directive’s effective date. The obligations imposed by this Airworthiness Directive include ensuring that all Harbin Y12 Series aeroplanes comply with the specified AFM revisions. Operators must ensure that the updated AFM is available and accessible to flight crew members, and they must initiate action to notify flight crews of these changes. This involves integrating the new procedures into training programs and ensuring that all operational personnel are aware of the updated requirements and limitations related to icing conditions. Failure to comply with the requirements of this Airworthiness Directive may result in civil or criminal consequences. While the specific penalties are not detailed in the AD, non-compliance with airworthiness directives can lead to enforcement actions by the Civil Aviation Safety Authority (CASA). Such actions can include fines, suspension or revocation of airworthiness certificates, and legal proceedings against the operator or individual responsible for the non-compliance. The severity of the penalties can vary based on the nature and extent of the non-compliance and its impact on aviation safety.

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Sourced from the Federal Register of Legislation at 26 August 2026. For the latest information on Australian Government law please go to https://www.legislation.gov.au.