DN Specifications
B. Runner Plank
IDNIYRA OFFICIAL SPECIFICATIONS
REVISED MAY 2024
Note: Dimensions are given in inches in the English System (except as noted) and in millimeters (MM) in the metric system.
B. RUNNER PLANK
1. Materials
1.a The allowed materials in runner plank construction are wood, fiberglass (as external reinforcement), adhesives (for gluing or lamination), and non structural cosmetic coatings.
2. Construction
2.a The number of wood laminations is optional.
2.b The cross Section is optional. Runner plank may be of hollow construction, but only wood or adhesives for lamination purposes may be used to comply with the minimum length, width, and thickness requirements in specifications B.3.a-f.
2.c Fiberglass and coatings may be added to the exterior of the wood plank after minimum length, widths and thicknesses are satisfied (specifications B.3.a-f). Added fiberglass and coatings shall not cause the runner plank to exceed the maximum length, width, and thickness (specifications B.3.a-f).
2.d The underside of the runner plank shall be higher at the centerline than the underside of the outside ends (“crown”). The profile of this crown shall form a fair continuous curve. Reversals of the curve are prohibited, and the curvature cannot be concave. Cutouts or depressions are prohibited.
3. Dimensions and Weight
English | Metric | |||
Max | Min | Max | Min | |
a. Length overall including hardware except pivot bolt. Max dimension refers to finished plank, min dimension refers to wood before adding reinforcements and external coatings. | 96 | 94 | 2438 | 2388 |
b. Minimum width along entire length of the plank. This measurement is of the wood runner plank and excludes exterior coatings or reinforcement if added. | 5.5 | 139.7 | ||
c. Maximum width along entire length of the plank including any exterior coatings and reinforcement if added. | 7.5 | 190.5 | ||
d. Minimum thickness over entire length except for fuselage centerline. This measurement is of the wood runner plank and excludes exterior coatings or reinforcement if added. | 1.0 | 25.4 | ||
e. Minimum thickness at fuselage centerline. This measurement is of the wood runner plank and excludes exterior coatings or reinforcement if added. | 1.125 | 28.6 | ||
f. Maximum thickness at any point including exterior coatings and reinforcement and excluding hull fitting pads. | 1.625 | 41.3 | ||
g. The runner plank, including all hardware and pivot bolts, shall not weigh less than 20 lbs. (9.1 kg.) | ||||
4. Measurement
4.a Specification B.3.a Length overall shall be measured in a straight line while not mounted on the fuselage and relaxed (under no load). The measurement shall be taken from the end of the runner plank or the chock, whichever gives the longer length; the measurement point may be different on different ends of the plank to determine the longest length. Overall length includes hardware but not pivot bolt.
4.d Specifications B.3.c. Areas of plank over the chock: The same fore and aft dimensions apply in this location. Fairings of any type in this area are not allowed if they extend outside the maximum width of the runner plank unless they are part of the chock. Fairings may be considered part of the chock only if the height (Specifications I.5.b) and materials (Specification I.13) requirements for the chock are satisfied. Small residual lines of adhesive between the plank and chock are acceptable.
Examples shown below. Localized buildups for chock mounting are excluded from the measurement.
