AD/AC/97 - Aircraft Flight Manual, Flight into Icing Conditions

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Legislation au F2006B02158 In force Legislative Instrument

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Twin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600 and 700) Series Aeroplanes

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 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.

AD/AC/97 Aircraft Flight Manual, Flight into Icing Conditions 3/2000

Applicability: Models 500, 500A, 500B, 500S, 500U, 520, 560, 560A, 560E, 560F, 680, 680E, 680FL(P), 680T, 680V, 680W, 681, 685, 690, 690A, 690B, 690C, 690D, 695, 695A,

695B, and 720, all serial numbers.

Requirement: Revise:

the Limitations Section of the aircraft's Aircraft Flight Manual (AFM) by incorporating the following:

"WARNING"

Severe icing may result from environmental conditions outside of those for which the aircraft is certificated.

Flight in freezing rain, freezing drizzle, or mixed icing conditions (super cooled liquid water and ice crystals) may result in:

ice build-up on protected surfaces and exceed the capability of the ice protection system, or

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 aircraft.

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

unusually extensive ice accumulation on the airframe and windscreen in areas not normally observed to collect ice, and/or

accumulation of ice on the lower surface of the wing aft of the protected area, and/or

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

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

All wing icing inspection lights must be operative prior to flight into known or forecast icing conditions at night. This direction supersedes any relief provided by any Minimum Equipment List.

2. the Normal Procedures Section of the approved AFM by incorporating the following:

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

Visible rain at temperatures below 0 degrees Celsius ambient air temperature;
Droplets that splash or splatter on impact at temperatures below 0 degrees Celsius ambient air temperature.

PROCEDURES FOR EXITING A SEVERE ICING

ENVIRONMENT: (These procedures are applicable to all flight phases from take-off to landing.)

Monitor the ambient air temperature.

While severe icing may form at temperatures as cold as -18 degrees Celsius, increased vigilance is warranted at temperatures around freezing when visible moisture is present.

If the visual cues which are specified in the Limitations Section of the AFM for identifying severe icing conditions are observed, accomplish the following:

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

Avoid abrupt and excessive manoeuvring that may exacerbate control difficulties.

Do not engage the autopilot.
If the autopilot had previously been engaged, hold the control wheel firmly and disengage the autopilot.

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

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 upper surface further aft on the wing than normal, possibly aft of the protected area.

If the flaps are extended, do not retract them until the airframe is clear of ice.
Report these weather conditions to Air Traffic Control.

Note 1: Certificate of Registration holders should initiate action to ensure notification of this change is conveyed to any person who may operate their aircraft as pilot in command.

Note 2: FAA AD 98-20-34 refers.

Certification for accomplishment of this Directive may be carried out:

after a copy of this Directive is included in the appropriate sections of the aircraft's AFM; and

b. may be carried out at a minimum, by the holder of a private pilot's licence.

Compliance: Within 30 days after the effective date of this Directive.

This Airworthiness Directive becomes effective on 23 March 2000.

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.

Eugene Paul Holzapfel

Delegate of the Civil Aviation Safety Authority 15 February 2000

The above AD is notified in the Commonwealth of Australia Gazette on 23 February 2000.

Overview

The Airworthiness Directive (AD) concerning Twin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600, and 700) Series Aeroplanes, issued under subregulation 39.1 (1) of the Civil Aviation Regulations 1998 (CAR 1998), was enacted in 2000 to address the significant safety concerns associated with operating these aircraft in severe icing conditions. This AD was introduced by the Civil Aviation Safety Authority (CASA), which is the regulatory body responsible for civil aviation safety in Australia. The directive aims to mitigate the risks of severe icing by specifying detailed limitations and procedures in the aircraft's Aircraft Flight Manual (AFM) to ensure pilots are aware of the conditions under which severe icing can occur and the necessary actions to take to maintain safe operations. The policy objective is to enhance the safety of flight operations by providing clearer guidance on how to handle severe icing conditions, thereby reducing the potential for accidents caused by ice accumulation on the aircraft.

Scope and Application

The Airworthiness Directive (AD) issued under the Civil Aviation Act 1988 applies specifically to the Twin Commander (Gulfstream/Rockwell/Aerocommander 500, 600, and 700) Series Aeroplanes, covering models 500 through 720 across all serial numbers. The directive mandates that holders of these aircraft revise the Aircraft Flight Manual (AFM) to incorporate updated limitations and procedures for flight into severe icing conditions, including visual cues for identifying such conditions and instructions for exiting them. This directive is enforceable under the Commonwealth jurisdiction and is aimed at ensuring that all aircraft of the specified series are operated within safe parameters when encountering severe icing conditions. Compliance with this directive is required within 30 days from its effective date of 23 March 2000, and adherence is critical to maintaining the airworthiness of these aircraft in potentially hazardous conditions.

Key Provisions

The Airworthiness Directive (AD) issued under subregulation 39.1(1) of the Civil Aviation Regulations 1998, specifically targets Twin Commander (Gulfstream/Rockwell/Aerocommander 500, 600, and 700) series aeroplanes. It mandates that the aircraft's Aircraft Flight Manual (AFM) be revised to include detailed information on flying in severe icing conditions, and to update normal procedures accordingly. This requirement applies to all models and serial numbers of the specified aircraft series. The directive mandates that the AFM's Limitations Section be revised to include a warning about severe icing, stating that environmental conditions outside the aircraft's certification may lead to ice build-up on surfaces, which can degrade performance and controllability. It advises pilots to immediately request priority handling from Air Traffic Control if visual cues of severe icing are observed, such as extensive ice accumulation in areas not normally affected. Additionally, the use of the autopilot is prohibited under these conditions to avoid masking tactile cues that might indicate adverse handling characteristics. The AD imposes several obligations on the aircraft operators and pilots. These include ensuring that the AFM is updated with the new severe icing conditions information and that all pilots operating the affected aircraft are made aware of these changes. The updated AFM must include a warning about severe icing, and specify visual cues that indicate such conditions, such as ice accumulation in unusual areas. Additionally, the Normal Procedures Section must be revised to include procedures for exiting severe icing conditions, such as requesting priority handling from Air Traffic Control and avoiding abrupt maneuvers. The AD also requires that wing icing inspection lights be operational before flight into known or forecast icing conditions at night, overriding any relief provided by the Minimum Equipment List. Failure to comply with the AD can result in significant consequences. The AD specifies that compliance must be achieved within 30 days from the effective date, which is 23 March 2000. While the specific penalties for non-compliance are not detailed in the text, it is implied that non-compliance could lead to the aircraft being deemed unairworthy, which would prevent it from being operated until the required changes are made. Additionally, operating the aircraft without the updated AFM could potentially lead to unsafe flight conditions, posing a risk to the safety of the aircraft and its occupants.

Area of Law: Aviation Law
Instrument: Legislative Instrument
Concepts: Definitions & Interpretation; Offence Provisions; Compliance Obligations

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