# Airworthiness Chapter 549 Appendix A - Maximum Allowable Wing Loading for a Fixed-Wing Aircraft with Flaps - Canadian Aviation Regulations (CARs)

Content last revised: 1998/02/17

## Appendix A - Maximum Allowable Wing Loading For A Fixed-Wing Aircraft With Flaps

### A549.1 General

This Appendix details the methods of calculating the maximum allowable wing loading and hence the maximum allowable take-off mass for a fixed-wing aircraft with flaps. The maximum allowable wing loading is calculated from the flap span ratio, flap chord ratio and flap deflection

Information note:

(Ref. section 549.103). ### A549.3 Flap Span Ratio, Flap Chord Ratio and Flap Deflection

The Flap Span Ratio (Rfs), Flap Chord Ratio (Rfc) and Flap Deflection (df) are calculated as follows:

1. (a) Flap Span Ratio :
1. The Flap Span Ratio (Rfs) is given by:
2. >R fs = 2 x b f / b
3. where:
4. bf = Span of One Flap, m (ft)
5. b = Wing Span, m (ft)
6. The value of the Flap Span Ratio shall not exceed: 0.75
2. (b) Flap Chord Ratio:
1. The Flap Chord Ratio (Rfc) is given by:
2. R fc= C f / C w
3. where:
4. Cf = Mean Flap Chord = (Sf / bf),m (ft);
5. Sf = Area of One Flap, m2 (ft2); and
6. Cw = Mean Wing Chord = (S / b), m (ft);
7. S = Wing Area, m2 (ft2).
8. The value of the Flap Chord Ratio shall not exceed: 0.25
3. (c) Flap Deflection:
1. The Flap Deflection (df) = number of degrees (o) of flap rotation from fully retracted position to fully extended position. The value of the Flap Deflection shall not exceed = 45o.