Federal Aviation Administration, DOT § 29.427

Federal Aviation Administration, DOT § 29.427 (b) Each primary control system, in- (2) Twist controls, 80R inch-pounds. cluding its supporting structure, must [Amdt. 29–12, 41 FR 55471, Dec. 20, 1976, as be designed as follows: amended by Amdt. 29–47, 66 FR 23538, May 9, (1) The system must withstand loads 2001] resulting from the limit pilot forces prescribed in § 29.397; § 29.399 Dual control system. (2) Notwithstanding paragraph (b)(3) Each dual primary flight control sys- of this section, when power-operated actuator controls or power boost con- tem must be able to withstand the trols are used, the system must also loads that result when pilot forces not withstand the loads resulting from the less than 0.75 times those obtained limit pilot forces prescribed in § 29.397 under § 29.395 are applied— in conjunction with the forces output (a) In opposition; and of each normally energized power de- (b) In the same direction. vice, including any single power boost § 29.411 Ground clearance: tail rotor or actuator system failure; guard. (3) If the system design or the normal operating loads are such that a part of (a) It must be impossible for the tail the system cannot react to the limit rotor to contact the landing surface pilot forces prescribed in § 29.397, that during a normal landing. part of the system must be designed to (b) If a tail rotor guard is required to withstand the maximum loads that can show compliance with paragraph (a) of be obtained in normal operation. The this section— minimum design loads must, in any (1) Suitable design loads must be es- case, provide a rugged system for serv- tablished for the guard: and ice use, including consideration of fa- (2) The guard and its supporting tigue, jamming, ground gusts, control structure must be designed to with- inertia, and friction loads. In the ab- stand those loads. sence of a rational analysis, the design loads resulting from 0.60 of the speci- § 29.427 Unsymmetrical loads. fied limit pilot forces are acceptable (a) Horizontal tail surfaces and their minimum design loads; and supporting structure must be designed (4) If operational loads may be ex- for unsymmetrical loads arising from ceeded through jamming, ground gusts, yawing and rotor wake effects in com- control inertia, or friction, the system bination with the prescribed flight con- must withstand the limit pilot forces ditions. specified in § 29.397, without yielding. (b) To meet the design criteria of [Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as paragraph (a) of this section, in the ab- amended by Amdt. 29–26, 55 FR 8002, Mar. 6, sence of more rational data, both of the 1990] following must be met: (1) One hundred percent of the max- § 29.397 Limit pilot forces and torques. imum loading from the symmetrical (a) Except as provided in paragraph flight conditions acts on the surface on (b) of this section, the limit pilot one side of the plane of symmetry, and forces are as follows: no loading acts on the other side. (1) For foot controls, 130 pounds. (2) Fifty percent of the maximum (2) For stick controls, 100 pounds fore loading from the symmetrical flight and aft, and 67 pounds laterally. conditions acts on the surface on each (b) For flap, tab, stabilizer, rotor side of the plane of symmetry, in oppo- brake, and landing gear operating con- site directions. trols, the following apply (R=radius in (c) For empennage arrangements inches): where the horizontal tail surfaces are (1) Crank wheel, and lever controls, [1 supported by the vertical tail surfaces, + R]/3 × 50 pounds, but not less than 50 the vertical tail surfaces and sup- pounds nor more than 100 pounds for porting structure must be designed for hand operated controls or 130 pounds the combined vertical and horizontal for foot operated controls, applied at surface loads resulting from each pre- any angle within 20 degrees of the scribed flight condition, considered plane of motion of the control. separately. The flight conditions must 735 VerDate Mar<15>2010 14:10 Mar 01, 2011 Jkt 223043 PO 00000 Frm 00745 Fmt 8010 Sfmt 8010 Y:\SGML\223043.XXX 223043 wwoods2 on DSK1DXX6B1PROD with CFR.

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