Chapter 4 - Preventative Measures and Deicing Procedures

Critical Surface Inspections

72.  Critical surface inspections should be performed immediately after final application of the anti-icing fluid to verify that the aircraft critical surfaces are free of contamination. Areas to be inspected depend on the aircraft design and should be identified in a critical surface inspection checklist. The checklist should include, at a minimum, all items recommended by the aircraft manufacturer. While some items may not be critical surfaces the following items:

• Wing leading edges, upper surfaces, and lower surfaces;
• Vertical and horizontal stabilizing devices, leading edges, upper surfaces, lower surfaces, and side panels;
• High lift devices such as leading edge slats and leading or trailing edge flaps;
• Spoilers and speed brakes;
• All control surfaces and control balance bays;
• Propellers;
• Engine inlets, particle separators, and screens;
• Windshields and other windows necessary for visibility;
• Antennae;
• Fuselage;
• Exposed instrumentation devices such as angle of attack vanes, pitot-static pressure probes and static ports;
• Fuel tanks and fuel cap vents;
• Cooling and APU air intakes, inlets, and exhausts; and
• Landing gear.

73.  Once it has been determined through the critical surface inspection that the aircraft is clean and adequately protected, the aircraft should be released for take-off as soon as possible. This procedure is especially important in conditions of precipitation or high relative humidity. Conversely, the pilot must be informed when contamination of the aircraft critical surfaces still exists and that further deicing is required. The pilot's decision to terminate the flight may be based solely upon information obtained from the Deicing Operator.

Note:  The "clean aircraft concept" policy is facilitated, in part, by the Critical Surface Inspection, which is a pre-flight external inspection of critical surfaces conducted by a qualified person, to determine if they are contaminated by frost, ice or snow.