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 (R_fs), Flap Chord Ratio (R_fc) and Flap Deflection (d_f) are calculated as follows:

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

A549.5 Maximum Allowable Wing Loading

Using the Flap Span Ratio (R_fs), the Flap Chord Ratio (R_fc) and the Flap Deflection(d_f) determined in A549.3, the maximum allowable wing loading is given by the equation (a) or (b), as applicable:

1. (a) For Use with S.I. (Metric) Units, the lesser of:
   1. M/S = 65.0 + (4.66 x (R_fs) x (R_fc) x (d_f)) kg/m²; or
   2. M/S = 100 kg/m².
2. (b) For Use with Imperial Units (fps), the lesser of:
   1. W/S = 13.3 + (0.96 x (R_fs) x (R_fc) x (d_f)) lb/ft²; or
   2. W/S = 20.4 lb/ft².