Taxi, Takeoff and Landing Roll Design Loads

Advisory

U.S. Deportment of Transportation

Circular

Federal Aviation Administration Subject: TAXI, TAKEOFF AND LANDING Date: 10/30/00 AC No: 25.491-1 ROLL DESIGN LOADS Initiated By: ANM-110 Change: 1. PURPOSE. This advisory circular (AC) sets forth acceptable methods of compliance with the provisions of part 25 of the Federal Aviation Regulations (FAR) dealing with the certification requirements for taxi, takeoff and landing roll design loads. Guidance information is provided for showing compliance with § 25.491 of the FAR, relating to structural design for airplane operation on paved runways and taxiways normally used in commercial operations.

Other methods of compliance with the requirements may be acceptable.

2. RELATED FAR SECTIONS. The contents of this AC are considered by the Federal Aviation Administration (FAA) in determining compliance with § 25.491 of the FAR. Related sections are §§ 25.305(c) and 25.235.

3. BACKGROUND.

a. All paved runways and taxiways have an inherent degree of surface unevenness, or roughness. This is the result of the normal tolerances of engineering standards required for construction, as well as the result of events such as uneven settlement and frost heave. In addition, repair of surfaces on an active runway or taxiway can result in temporary ramped surfaces. Many countries have developed criteria for runway surface roughness. The International Civil Aviation Organization (ICAO) standards are published in ICAO Annex 14.

b. In the late 1940's, as airplanes became larger, more flexible, and operated at higher ground speeds, consideration of dynamic loads during taxi, landing rollout, and takeoff became important in airplane design. The Civil Aeronautics Administration, in Civil Air Regulations 4b (CAR 4b), § 4b.172, required the effects of landing gear deflection during taxiing over the roughest ground expected in service to be considered relative to its effect on damage to structural components. The CAR 4b, § 4b.235, also required the airplane be designed, in part, to withstand loads calculated under § 4b.172. Those regulations were carried over to part 25 of the FAR as § 25.235 and § 25.491 respectively. Substantiation of the effect of ground loads on flexible structure is required by § 25.305(c).

AC 25.491-1 10/30/00 c. Several approaches had been taken by different manufacturers in complying with the noted regulations. If dynamic effects due to rigid body modes or airframe flexibility during taxi were not considered critical, some manufacturers used a simplified static analysis where a static inertia force was applied to the airplane using a load factor of 2.0 for single axle gears or 1.7 for multiple axle gears. The lower 1.7 factor was justified based on an assumption that there was a load alleviating effect resulting from rotation of the beam, on which the forward and aft axles are attached, about the central pivot point on the strut. The static load factor approach was believed to encompass any dynamic effects and it had the benefit of a relatively simple analysis.

d. As computers became more powerful and dynamic analysis methods became more sophisticated, it was found that dynamic effects sometimes resulted in loads greater than those which were predicted by the static criterion. Some manufacturers performed calculations using a series of harmonic bumps to represent a runway surface, tuning the bumps to excite various portions of the structure at a given speed. U.S. Military Standard 8862 defines amplitude and wavelengths of 1-cosine bumps intended to excite low speed plunge, pitch and wing first bending modes.

e. Some manufacturers used actual runway profile data to calculate loads. The runway profiles of the San Francisco Runway 28R or Anchorage Runway 24, which were known to cause high loads on airplanes and were the subject of pilot complaints until resurfaced, have been used in a series of bi-directional constant speed analytical runs to determine loads. In some cases, accelerated runs have been used, starting from several points along the runway. The profiles of those runways are described in NASA Reports CR-119 and TN D-5703. Such deterministic dynamic analyses have in general proved to be satisfactory.

f. Some manufacturers have used a statistical power spectral density (PSD) approach, especially to calculate fatigue loads. Extensive PSD runway roughness data exist for numerous world runways. The PSD approach is not considered practical for calculation of limit loads.

g. Because the various methods described above produce different results, the guidance information given in paragraphs 4, 5, and 6 of this AC should be used when demonstrating compliance with § 25.491.

4. RUNWAY PROFILE CONDITION .

a. Consideration of airframe flexibility and landing gear dynamic characteristics is necessary in most cases. A deterministic dynamic analysis, based on the San Francisco Runway 28R (before it was resurfaced), described in Table 1 of this AC, is an acceptable method for compliance. As an alternative means of compliance, the San Francisco Runway 28R (before it was resurfaced) may be used with the severe bump from 1530 to 1538 feet modified per Table 2. The modifications to the bump reflect the maximum slope change permitted in ICAO Annex 14 for temporary ramps used to transition asphalt overlays to existing pavement. The points affected by this modification are outlined in Table 1.

10/30/00 AC 25.491-1 b. Airplane design loads should be developed for the most critical conditions arising from taxi, takeoff, and landing run. The airplane analysis model should include significant airplane rigid body and flexible modes, and the appropriate landing gear and tire characteristics. Unless the airplane has design features that would result in significant asymmetric loads, only the symmetric cases need be investigated.

c. Airplane steady aerodynamic effects should normally be included. However, they may be ignored if their deletion is shown to produce conservative loads. Unsteady aerodynamic effects on dynamic response may be neglected.

d. Conditions should be run at the maximum takeoff weight and the maximum landing weight with critical combinations of wing fuel, payload, and extremes of center of gravity (c.g.) range.

For airplanes with trimable stabilizers, the stabilizer should be at the appropriate setting for takeoff cases and at the recommended final approach setting for landing cases. The elevator should be assumed faired relative to the stabilizer throughout the takeoff or landing run, unless other normal procedures are specified in the flight manual.

e. A series of constant speed runs should be made in both directions from 20 knots up to the maximum ground speeds expected in normal operation (V defined at maximum altitude and R temperature for takeoff conditions, 1.25 V for landing conditions). Sufficiently small speed L2 increments should be evaluated to assure that maximum loads are achieved. Constant speed runs should be made because using accelerated runs may not define the speed/roughness points which could produce peak dynamic loads. For maximum take-off weight cases, the analysis should account for normal takeoff flap and control settings and consider both zero and maximum thrust. For maximum landing weight cases, the analysis should account for normal flap and spoiler positions following landing, and steady pitching moments equivalent to those produced by braking with a coefficient of friction of 0.3 with and without reverse thrust. The effects of automatic braking systems that reduce braking in the presence of reverse thrust may be taken into account.

5. DISCRETE LOAD CONDITION . One of the following discrete limit load conditions should be evaluated: a. With all landing gears in contact with the ground, the condition of a vertical load equal to 1.7 times the static ground reaction should be investigated under the most adverse airplane loading distribution at maximum takeoff weight, with and without thrust from the engines; b. As an alternative to paragraph 5(a) above, it would be acceptable to undertake dynamic analyses under the same conditions considered in paragraph 4 of this AC considering the aircraft response to each of the following pairs of identical and contiguous 1-cosine upwards bumps on an otherwise smooth runway: AC 25.491-1 10/30/00 (i) Bump wavelengths equal to the mean longitudinal distance between nose and main landing gears, or between the main and tail landing gears, as appropriate; and separately.

(ii) Bump wavelengths equal to twice this distance.

The bump height in each case should be defined as: H = 1.2 + 0.023 L Where -- H = the bump height (inches) L =the bump wavelength (inches) 6. COMBINED LOAD CONDITION . A condition of combined vertical, side and drag loads should be investigated for the main landing gear. In the absence of a more rational analysis a vertical load equal to 90% of the ground reaction from paragraph 5 above should be combined with a drag load of 20% of the vertical load and a side load of 20% of the vertical load. Side loads acting either direction should be considered.

7. TIRE CONDITIONS . The calculation of maximum gear loads in accordance with paragraphs 4, 5, and 6, may be performed using fully inflated tires. For multiple wheel units, the maximum gear loads should be distributed between the wheels in accordance with the criteria of § 25.511.

10/30/00 AC 25.491-1 TABLE 1 SAN FRANCISCO RUNWAY 28R ONE TRACK LENGTH: 3880 FEET NUMBER OF POINTS: 1941 POINT SPACING: 2 FEET ELEVATIONS: FEET REFERENCE SOURCE: REPORT TO NASA (EFFECTS OF RUNWAY UNEVENNESS ON THE DYNAMIC RESPONSE OF SUPERSONIC TRANSPORTS), JULY 1964, U. OF CALIF. BERKLEY.

RUNWAY ELEVATION POINTS IN FEET: Dist. Elev. Dist. Elev. Dist. Elev. Dist. Elev. Dist. Elev.

0 10.3 776 10.99 1552 10.92 2328 11.16 3104 11.93 2 10.31 778 10.98 1554 10.92 2330 11.15 3106 11.92 4 10.3 780 10.99 1556 10.91 2332 11.14 3108 11.92 6 10.3 782 10.99 1558 10.93 2334 11.14 3110 11.92 8 10.31 784 11 1560 10.93 2336 11.14 3112 11.92 10 10.32 786 11.01 1562 10.93 2338 11.14 3114 11.92 12 10.33 788 11.01 1564 10.93 2340 11.14 3116 11.92 14 10.34 790 11.01 1566 10.93 2342 11.14 3118 11.92 16 10.35 792 11.03 1568 10.93 2344 11.15 3120 11.92 18 10.36 794 11.04 1570 10.93 2346 11.15 3122 11.92 20 10.36 796 11.03 1572 10.93 2348 11.15 3124 11.92 22 10.37 798 11.05 1574 10.93 2350 11.15 3126 11.92 24 10.37 800 11.06 1576 10.93 2352 11.15 3128 11.91 26 10.37 802 11.07 1578 10.93 2354 11.15 3130 11.9 28 10.38 804 11.06 1580 10.94 2356 11.16 3132 11.9 30 10.39 806 11.07 1582 10.94 2358 11.16 3134 11.9 32 10.4 808 11.08 1584 10.94 2360 11.15 3136 11.9 34 10.4 810 11.08 1586 10.94 2362 11.15 3138 11.9 36 10.41 812 11.08 1588 10.95 2364 11.16 3140 11.9 38 10.41 814 11.09 1590 10.94 2366 11.16 3142 11.9 40 10.42 816 11.09 1592 10.93 2368 11.16 3144 11.9 42 10.43 818 11.08 1594 10.94 2370 11.16 3146 11.9 44 10.43 820 11.08 1596 10.94 2372 11.16 3148 11.9 46 10.44 822 11.08 1598 10.93 2374 11.16 3150 11.9 48 10.44 824 11.08 1600 10.92 2376 11.16 3152 11.9 50 10.44 826 11.08 1602 10.92 2378 11.16 3154 11.9 52 10.44 828 11.08 1604 10.92 2380 11.17 3156 11.9 54 10.44 830 11.07 1606 10.91 2382 11.17 3158 11.9 56 10.45 832 11.08 1608 10.91 2384 11.17 3160 11.9 58 10.46 834 11.08 1610 10.91 2386 11.17 3162 11.89 60 10.47 836 11.08 1612 10.91 2388 11.17 3164 11.88 62 10.47 838 11.08 1614 10.9 2390 11.17 3166 11.88 64 10.48 840 11.09 1616 10.89 2392 11.17 3168 11.87 66 10.49 842 11.08 1618 10.88 2394 11.16 3170 11.87 * 68 10.49 844 11.08 1620 10.87 2396 11.15 3172 11.86 70 10.5 846 11.07 1622 10.89 2398 11.15 3174 11.86 72 10.5 848 11.07 1624 10.88 2400 11.14 3176 11.85 74 10.5 850 11.06 1626 10.88 2402 11.14 3178 11.85 76 10.5 852 11.05 1628 10.88 2404 11.14 3180 11.84 AC 25.491-1 10/30/00 78 10.5 854 11.05 1630 10.87 2406 11.13 3182 11.84 80 10.5 856 11.04 1632 10.86 2408 11.12 3184 11.84 82 10.49 858 11.05 1634 10.85 2410 11.12 3186 11.84 84 10.49 860 11.04 1636 10.86 2412 11.12 3188 11.84 86 10.49 862 11.04 1638 10.86 2414 11.12 3190 11.85 88 10.49 864 11.04 1640 10.85 2416 11.12 3192 11.87 90 10.5 866 11.04 1642 10.85 2418 11.12 3194 11.89 92 10.5 868 11.04 1644 10.85 2420 11.13 3196 11.89 94 10.51 870 11.04 1646 10.84 2422 11.13 3198 11.9 96 10.51 872 11.04 1648 10.84 2424 11.14 3200 11.89 98 10.52 874 11.03 1650 10.84 2426 11.15 3202 11.92 100 10.52 876 11.03 1652 10.83 2428 11.16 3204 11.95 102 10.52 878 11.03 1654 10.83 2430 11.17 3206 11.95 104 10.53 880 11.03 1656 10.82 2432 11.18 3208 11.95 106 10.53 882 11.02 1658 10.82 2434 11.19 3210 11.94 108 10.54 884 11.02 1660 10.81 2436 11.2 3212 11.94 110 10.54 886 11.02 1662 10.81 2438 11.2 3214 11.93 112 10.55 888 11.02 1664 10.8 2440 11.22 3216 11.92 114 10.55 890 11.02 1666 10.79 2442 11.23 3218 11.92 116 10.55 892 11.02 1668 10.79 2444 11.24 3220 11.91 118 10.55 894 11.03 1670 10.79 2446 11.24 3222 11.9 120 10.54 896 11.03 1672 10.79 2448 11.25 3224 11.9 122 10.55 898 11.04 1674 10.79 2450 11.26 3226 11.89 124 10.55 900 11.05 1676 10.79 2452 11.27 3228 11.88 126 10.56 902 11.05 1678 10.8 2454 11.28 3230 11.87 128 10.57 904 11.06 1680 10.8 2456 11.28 3232 11.86 130 10.57 906 11.06 1682 10.81 2458 11.29 3234 11.85 132 10.57 908 11.06 1684 10.82 2460 11.3 3236 11.84 134 10.57 910 11.07 1686 10.82 2462 11.3 3238 11.84 136 10.57 912 11.07 1688 10.83 2464 11.3 3240 11.84 138 10.58 914 11.07 1690 10.84 2466 11.31 3242 11.83 140 10.57 916 11.07 1692 10.85 2468 11.3 3244 11.82 142 10.57 918 11.07 1694 10.85 2470 11.31 3246 11.82 144 10.58 920 11.08 1696 10.85 2472 11.31 3248 11.81 146 10.57 922 11.08 1698 10.87 2474 11.31 3250 11.83 148 10.56 924 11.07 1700 10.87 2476 11.31 3252 11.83 150 10.56 926 11.07 1702 10.88 2478 11.3 3254 11.83 152 10.56 928 11.07 1704 10.87 2480 11.3 3256 11.84 154 10.56 930 11.06 1706 10.88 2482 11.3 3258 11.84 156 10.56 932 11.06 1708 10.87 2484 11.29 3260 11.84 158 10.56 934 11.06 1710 10.87 2486 11.29 3262 11.84 160 10.56 936 11.06 1712 10.87 2488 11.29 3264 11.82 162 10.56 938 11.06 1714 10.87 2490 11.29 3266 11.83 164 10.55 940 11.07 1716 10.86 2492 11.29 3268 11.82 166 10.55 942 11.07 1718 10.85 2494 11.29 3270 11.83 168 10.55 944 11.08 1720 10.84 2496 11.29 3272 11.83 170 10.56 946 11.08 1722 10.84 2498 11.29 3274 11.84 172 10.57 948 11.09 1724 10.84 2500 11.29 3276 11.84 174 10.57 950 11.09 1726 10.84 2502 11.3 3278 11.84 176 10.57 952 11.09 1728 10.84 2504 11.3 3280 11.85 178 10.57 954 11.09 1730 10.83 2506 11.31 3282 11.84 180 10.56 956 11.1 1732 10.82 2508 11.31 3284 11.84 182 10.55 958 11.09 1734 10.82 2510 11.32 3286 11.84 10/30/00 AC 25.491-1 Dist. Elev. Dist. Elev. Dist. Elev. Dist. Elev. Dist. Elev.

184 10.55 960 11.09 1736 10.82 2512 11.32 3288 11.85 186 10.55 962 11.09 1738 10.82 2514 11.33 3290 11.85 188 10.55 964 11.09 1740 10.82 2516 11.33 3292 11.85 190 10.55 966 11.08 1742 10.82 2518 11.34 3294 11.86 192 10.56 968 11.08 1744 10.83 2520 11.35 3296 11.86 194 10.56 970 11.07 1746 10.82 2522 11.35 3298 11.84 196 10.56 972 11.07 1748 10.83 2524 11.35 3300 11.84 198 10.56 974 11.06 1750 10.82 2526 11.35 3302 11.84 200 10.55 976 11.07 1752 10.82 2528 11.35 3304 11.84 202 10.54 978 11.09 1754 10.82 2530 11.35 3306 11.84 204 10.53 980 11.1 1756 10.82 2532 11.36 3308 11.84 206 10.52 982 11.1 1758 10.81 2534 11.36 3310 11.84 208 10.52 984 11.11 1760 10.81 2536 11.35 3312 11.84 210 10.52 986 11.11 1762 10.81 2538 11.35 3314 11.84 212 10.52 988 11.12 1764 10.81 2540 11.35 3316 11.84 214 10.52 990 11.12 1766 10.82 2542 11.35 3318 11.84 216 10.52 992 11.12 1768 10.82 2544 11.35 3320 11.84 218 10.53 994 11.11 1770 10.82 2546 11.35 3322 11.83 220 10.52 996 11.11 1772 10.83 2548 11.34 3324 11.83 222 10.52 998 11.11 1774 10.83 2550 11.34 3326 11.83 224 10.51 1000 11.11 1776 10.83 2552 11.34 3328 11.82 226 10.52 1002 11.11 1778 10.84 2554 11.34 3330 11.83 228 10.52 1004 11.1 1780 10.84 2556 11.35 3332 11.83 230 10.51 1006 11.11 1782 10.85 2558 11.35 3334 11.83 232 10.52 1008 11.11 1784 10.86 2560 11.35 3336 11.82 234 10.52 1010 11.12 1786 10.86 2562 11.34 3338 11.82 236 10.53 1012 11.12 1788 10.86 2564 11.33 3340 11.83 238 10.53 1014 11.12 1790 10.88 2566 11.33 3342 11.82 240 10.53 1016 11.11 1792 10.87 2568 11.33 3344 11.83 242 10.53 1018 11.11 1794 10.86 2570 11.33 3346 11.83 244 10.53 1020 11.12 1796 10.86 2572 11.33 3348 11.84 246 10.53 1022 11.11 1798 10.86 2574 11.33 3350 11.84 248 10.53 1024 11.11 1800 10.87 2576 11.33 3352 11.83 250 10.53 1026 11.11 1802 10.87 2578 11.32 3354 11.83 252 10.53 1028 11.1 1804 10.86 2580 11.33 3356 11.83 254 10.52 1030 11.1 1806 10.85 2582 11.33 3358 11.83 256 10.53 1032 11.12 1808 10.85 2584 11.33 3360 11.83 258 10.54 1034 11.13 1810 10.89 2586 11.33 3362 11.84 260 10.54 1036 11.15 1812 10.91 2588 11.33 3364 11.84 262 10.54 1038 11.16 1814 10.91 2590 11.34 3366 11.84 264 10.54 1040 11.17 1816 10.92 2592 11.34 3368 11.85 266 10.54 1042 11.18 1818 10.92 2594 11.34 3370 11.85 268 10.54 1044 11.18 1820 10.93 2596 11.35 3372 11.85 270 10.55 1046 11.19 1822 10.93 2598 11.35 3374 11.85 272 10.55 1048 11.19 1824 10.93 2600 11.35 3376 11.84 274 10.54 1050 11.2 1826 10.94 2602 11.35 3378 11.84 276 10.55 1052 11.22 1828 10.94 2604 11.35 3380 11.85 278 10.55 1054 11.22 1830 10.95 2606 11.35 3382 11.85 280 10.56 1056 11.23 1832 10.94 2608 11.35 3384 11.86 282 10.57 1058 11.23 1834 10.93 2610 11.35 3386 11.86 284 10.58 1060 11.23 1836 10.93 2612 11.36 3388 11.87 286 10.59 1062 11.24 1838 10.92 2614 11.36 3390 11.87 AC 25.491-1 10/30/00 288 10.6 1064 11.25 1840 10.93 2616 11.36 3392 11.87 290 10.61 1066 11.25 1842 10.91 2618 11.35 3394 11.87 292 10.62 1068 11.26 1844 10.91 2620 11.35 3396 11.87 294 10.63 1070 11.24 1846 10.9 2622 11.35 3398 11.86 296 10.65 1072 11.27 1848 10.9 2624 11.35 3400 11.87 298 10.66 1074 11.28 1850 10.9 2626 11.35 3402 11.87 300 10.66 1076 11.28 1852 10.91 2628 11.35 3404 11.88 302 10.67 1078 11.3 1854 10.91 2630 11.36 3406 11.89 304 10.66 1080 11.31 1856 10.89 2632 11.36 3408 11.89 306 10.67 1082 11.32 1858 10.9 2634 11.36 3410 11.89 308 10.67 1084 11.33 1860 10.91 2636 11.36 3412 11.91 310 10.67 1086 11.34 1862 10.91 2638 11.36 3414 11.91 312 10.67 1088 11.34 1864 10.91 2640 11.37 3416 11.92 314 10.67 1090 11.34 1866 10.92 2642 11.38 3418 11.93 316 10.66 1092 11.34 1868 10.93 2644 11.38 3420 11.95 318 10.66 1094 11.33 1870 10.94 2646 11.39 3422 11.95 320 10.65 1096 11.32 1872 10.94 2648 11.39 3424 11.96 322 10.65 1098 11.32 1874 10.94 2650 11.4 3426 11.96 324 10.65 1100 11.31 1876 10.94 2652 11.41 3428 11.96 326 10.65 1102 11.32 1878 10.94 2654 11.42 3430 11.96 328 10.66 1104 11.32 1880 10.95 2656 11.42 3432 11.95 330 10.67 1106 11.31 1882 10.93 2658 11.43 3434 11.96 332 10.67 1108 11.31 1884 10.93 2660 11.43 3436 11.96 334 10.67 1110 11.31 1886 10.93 2662 11.42 3438 11.96 336 10.68 1112 11.32 1888 10.93 2664 11.42 3440 11.96 338 10.68 1114 11.31 1890 10.92 2666 11.43 3442 11.95 340 10.68 1116 11.32 1892 10.93 2668 11.43 3444 11.95 342 10.69 1118 11.33 1894 10.93 2670 11.43 3446 11.94 344 10.69 1120 11.34 1896 10.93 2672 11.43 3448 11.96 346 10.69 1122 11.35 1898 10.93 2674 11.43 3450 11.98 348 10.7 1124 11.35 1900 10.91 2676 11.43 3452 11.99 350 10.71 1126 11.36 1902 10.9 2678 11.44 3454 12.01 352 10.71 1128 11.36 1904 10.91 2680 11.44 3456 12.03 354 10.72 1130 11.36 1906 10.91 2682 11.45 3458 12.04 356 10.72 1132 11.37 1908 10.91 2684 11.46 3460 12.05 358 10.71 1134 11.37 1910 10.91 2686 11.46 3462 12.05 360 10.72 1136 11.37 1912 10.91 2688 11.47 3464 12.05 362 10.72 1138 11.37 1914 10.91 2690 11.48 3466 12.05 364 10.72 1140 11.38 1916 10.91 2692 11.48 3468 12.05 366 10.71 1142 11.38 1918 10.9 2694 11.49 3470 12.05 368 10.72 1144 11.38 1920 10.9 2696 11.49 3472 12.04 370 10.72 1146 11.38 1922 10.89 2698 11.5 3474 12.06 372 10.73 1148 11.38 1924 10.9 2700 11.5 3476 12.06 374 10.73 1150 11.38 1926 10.9 2702 11.51 3478 12.07 376 10.74 1152 11.38 1928 10.9 2704 11.52 3480 12.07 378 10.75 1154 11.38 1930 10.91 2706 11.52 3482 12.07 380 10.75 1156 11.38 1932 10.9 2708 11.52 3484 12.07 382 10.78 1158 11.37 1934 10.91 2710 11.52 3486 12.06 384 10.77 1160 11.37 1936 10.89 2712 11.52 3488 12.07 386 10.78 1162 11.37 1938 10.89 2714 11.52 3490 12.07 388 10.79 1164 11.37 1940 10.89 2716 11.52 3492 12.08 390 10.8 1166 11.38 1942 10.89 2718 11.52 3494 12.08 392 10.81 1168 11.38 1944 10.89 2720 11.52 3496 12.08 10/30/00 AC 25.491-1 Dist. Elev. Dist. Elev. Dist. Elev. Dist. Elev. Dist. Elev.

394 10.81 1170 11.39 1946 10.88 2722 11.52 3498 12.09 396 10.82 1172 11.38 1948 10.88 2724 11.51 3500 12.09 398 10.83 1174 11.38 1950 10.87 2726 11.51 3502 12.08 400 10.84 1176 11.39 1952 10.87 2728 11.51 3504 12.08 402 10.85 1178 11.4 1954 10.87 2730 11.5 3506 12.08 404 10.86 1180 11.41 1956 10.86 2732 11.5 3508 12.08 406 10.86 1182 11.41 1958 10.88 2734 11.5 3510 12.08 408 10.86 1184 11.42 1960 10.87 2736 11.5 3512 12.09 410 10.86 1186 11.43 1962 10.86 2738 11.51 3514 12.1 412 10.85 1188 11.44 1964 10.87 2740 11.51 3516 12.1 414 10.86 1190 11.44 1966 10.87 2742 11.51 3518 12.1 416 10.86 1192 11.45 1968 10.86 2744 11.52 3520 12.1 418 10.87 1194 11.46 1970 10.85 2746 11.52 3522 12.1 420 10.87 1196 11.46 1972 10.85 2748 11.52 3524 12.11 422 10.87 1198 11.46 1974 10.85 2750 11.52 3526 12.11 424 10.87 1200 11.46 1976 10.86 2752 11.53 3528 12.12 426 10.87 1202 11.47 1978 10.85 2754 11.53 3530 12.13 428 10.86 1204 11.48 1980 10.86 2756 11.53 3532 12.13 430 10.85 1206 11.48 1982 10.86 2758 11.52 3534 12.13 432 10.84 1208 11.48 1984 10.86 2760 11.52 3536 12.13 434 10.84 1210 11.49 1986 10.87 2762 11.52 3538 12.14 436 10.83 1212 11.5 1988 10.87 2764 11.52 3540 12.14 438 10.83 1214 11.5 1990 10.87 2766 11.52 3542 12.13 440 10.84 1216 11.5 1992 10.87 2768 11.52 3544 12.13 442 10.85 1218 11.5 1994 10.87 2770 11.53 3546 12.13 444 10.86 1220 11.5 1996 10.88 2772 11.53 3548 12.11 446 10.87 1222 11.5 1998 10.87 2774 11.53 3550 12.1 448 10.87 1224 11.49 2000 10.88 2776 11.54 3552 12.07 450 10.88 1226 11.49 2002 10.87 2778 11.53 3554 12.06 452 10.89 1228 11.49 2004 10.88 2780 11.53 3556 12.07 454 10.9 1230 11.48 2006 10.88 2782 11.54 3558 12.08 456 10.92 1232 11.47 2008 10.88 2784 11.54 3560 12.09 458 10.93 1234 11.46 2010 10.88 2786 11.54 3562 12.1 460 10.94 1236 11.46 2012 10.88 2788 11.54 3564 12.11 462 10.95 1238 11.48 2014 10.89 2790 11.53 3566 12.11 464 10.95 1240 11.46 2016 10.9 2792 11.53 3568 12.12 466 10.95 1242 11.47 2018 10.89 2794 11.53 3570 12.06 468 10.95 1244 11.47 2020 10.89 2796 11.53 3572 12.01 470 10.95 1246 11.47 2022 10.89 2798 11.54 3574 12.03 472 10.95 1248 11.47 2024 10.89 2800 11.54 3576 12.04 474 10.96 1250 11.46 2026 10.9 2802 11.54 3578 12.05 476 10.97 1252 11.45 2028 10.89 2804 11.55 3580 12.05 478 10.98 1254 11.45 2030 10.89 2806 11.55 3582 12.06 480 10.98 1256 11.45 2032 10.88 2808 11.55 3584 12.06 482 10.99 1258 11.46 2034 10.87 2810 11.56 3586 12.05 484 10.99 1260 11.46 2036 10.88 2812 11.55 3588 12.04 486 10.99 1262 11.46 2038 10.87 2814 11.55 3590 12.03 488 11 1264 11.45 2040 10.87 2816 11.55 3592 12.02 490 11.01 1266 11.45 2042 10.87 2818 11.55 3594 12.02 492 11.01 1268 11.45 2044 10.87 2820 11.54 3596 12.02 494 11.01 1270 11.45 2046 10.88 2822 11.53 3598 12.02 496 11.01 1272 11.45 2048 10.88 2824 11.53 3600 12.01 AC 25.491-1 10/30/00 498 10.98 1274 11.46 2050 10.88 2826 11.53 3602 11.99 500 10.96 1276 11.46 2052 10.88 2828 11.51 3604 11.98 502 10.95 1278 11.46 2054 10.88 2830 11.52 3606 11.94 504 10.95 1280 11.48 2056 10.88 2832 11.52 3608 11.94 506 10.95 1282 11.47 2058 10.89 2834 11.53 3610 11.93 508 10.96 1284 11.47 2060 10.89 2836 11.53 3612 11.93 510 10.97 1286 11.48 2062 10.89 2838 11.54 3614 11.92 512 10.97 1288 11.48 2064 10.89 2840 11.55 3616 11.91 514 10.98 1290 11.48 2066 10.89 2842 11.56 3618 11.9 516 10.97 1292 11.48 2068 10.89 2844 11.56 3620 11.9 518 10.97 1294 11.49 2070 10.89 2846 11.57 3622 11.9 520 10.98 1296 11.49 2072 10.88 2848 11.57 3624 11.9 522 10.99 1298 11.5 2074 10.88 2850 11.57 3626 11.9 524 11 1300 11.51 2076 10.89 2852 11.58 3628 11.91 526 11.01 1302 11.52 2078 10.88 2854 11.58 3630 11.9 528 11.03 1304 11.52 2080 10.89 2856 11.58 3632 11.88 530 11.03 1306 11.52 2082 10.88 2858 11.58 3634 11.87 532 11.03 1308 11.52 2084 10.88 2860 11.58 3636 11.87 534 11.03 1310 11.52 2086 10.88 2862 11.58 3638 11.86 536 11.03 1312 11.52 2088 10.88 2864 11.59 3640 11.86 538 11.03 1314 11.52 2090 10.88 2866 11.59 3642 11.85 540 11.03 1316 11.53 2092 10.87 2868 11.59 3644 11.86 542 11.03 1318 11.52 2094 10.87 2870 11.59 3646 11.86 544 11.02 1320 11.52 2096 10.87 2872 11.58 3648 11.85 546 11.02 1322 11.52 2098 10.87 2874 11.57 3650 11.85 548 11.03 1324 11.53 2100 10.87 2876 11.57 3652 11.85 550 11.04 1326 11.53 2102 10.88 2878 11.58 3654 11.86 552 11.05 1328 11.53 2104 10.88 2880 11.57 3656 11.86 554 11.05 1330 11.53 2106 10.88 2882 11.57 3658 11.87 556 11.04 1332 11.53 2108 10.89 2884 11.57 3660 11.86 558 11.06 1334 11.53 2110 10.89 2886 11.58 3662 11.86 560 11.07 1336 11.54 2112 10.9 2888 11.58 3664 11.85 562 11.07 1338 11.53 2114 10.91 2890 11.59 3666 11.84 564 11.08 1340 11.52 2116 10.92 2892 11.6 3668 11.85 566 11.08 1342 11.52 2118 10.92 2894 11.62 3670 11.85 568 11.09 1344 11.51 2120 10.93 2896 11.61 3672 11.87 570 11.1 1346 11.53 2122 10.92 2898 11.61 3674 11.89 572 11.12 1348 11.52 2124 10.92 2900 11.61 3676 11.88 574 11.13 1350 11.54 2126 10.92 2902 11.61 3678 11.88 576 11.14 1352 11.53 2128 10.92 2904 11.61 3680 11.88 578 11.14 1354 11.54 2130 10.92 2906 11.62 3682 11.89 580 11.15 1356 11.53 2132 10.92 2908 11.63 3684 11.9 582 11.16 1358 11.54 2134 10.92 2910 11.64 3686 11.91 584 11.17 1360 11.53 2136 10.93 2912 11.65 3688 11.91 586 11.17 1362 11.54 2138 10.93 2914 11.66 3690 11.91 588 11.17 1364 11.55 2140 10.93 2916 11.67 3692 11.91 590 11.17 1366 11.54 2142 10.93 2918 11.67 3694 11.92 592 11.17 1368 11.54 2144 10.93 2920 11.67 3696 11.92 594 11.18 1370 11.54 2146 10.94 2922 11.68 3698 11.93 596 11.18 1372 11.54 2148 10.93 2924 11.7 3700 11.94 598 11.18 1374 11.53 2150 10.93 2926 11.72 3702 11.94 600 11.17 1376 11.52 2152 10.93 2928 11.73 3704 11.95 602 11.17 1378 11.51 2154 10.93 2930 11.74 3706 11.95 10/30/00 AC 25.491-1 Dist. Elev. Dist. Elev. Dist. Elev. Dist. Elev. Dist. Elev.

604 11.17 1380 11.5 2156 10.93 2932 11.76 3708 11.95 606 11.17 1382 11.49 2158 10.92 2934 11.77 3710 11.95 608 11.19 1384 11.49 2160 10.92 2936 11.78 3712 11.95 610 11.17 1386 11.49 2162 10.91 2938 11.8 3714 11.96 612 11.18 1388 11.49 2164 10.9 2940 11.82 3716 11.95 614 11.18 1390 11.49 2166 10.92 2942 11.82 3718 11.95 616 11.18 1392 11.48 2168 10.91 2944 11.82 3720 11.96 618 11.19 1394 11.47 2170 10.91 2946 11.83 3722 11.97 620 11.19 1396 11.47 2172 10.9 2948 11.82 3724 11.98 622 11.19 1398 11.47 2174 10.9 2950 11.82 3726 11.98 624 11.2 1400 11.46 2176 10.9 2952 11.83 3728 11.99 626 11.21 1402 11.47 2178 10.88 2954 11.84 3730 12 628 11.21 1404 11.47 2180 10.88 2956 11.83 3732 12 630 11.21 1406 11.48 2182 10.86 2958 11.83 3734 11.99 632 11.2 1408 11.47 2184 10.85 2960 11.83 3736 11.99 634 11.2 1410 11.46 2186 10.85 2962 11.83 3738 11.99 636 11.2 1412 11.46 2188 10.84 2964 11.83 3740 12 638 11.19 1414 11.46 2190 10.84 2966 11.83 3742 12 640 11.18 1416 11.46 2192 10.84 2968 11.84 3744 12.01 642 11.18 1418 11.46 2194 10.84 2970 11.85 3746 12.02 644 11.17 1420 11.47 2196 10.85 2972 11.86 3748 12.02 646 11.16 1422 11.47 2198 10.85 2974 11.87 3750 12.03 648 11.15 1424 11.47 2200 10.85 2976 11.88 3752 12.04 650 11.14 1426 11.46 2202 10.85 2978 11.88 3754 12.05 652 11.14 1428 11.46 2204 10.85 2980 11.89 3756 12.06 654 11.14 1430 11.44 2206 10.85 2982 11.9 3758 12.06 656 11.12 1432 11.43 2208 10.86 2984 11.9 3760 12.06 658 11.11 1434 11.41 2210 10.86 2986 11.9 3762 12.06 660 11.09 1436 11.4 2212 10.86 2988 11.9 3764 12.06 662 11.09 1438 11.39 2214 10.87 2990 11.9 3766 12.06 664 11.09 1440 11.38 2216 10.88 2992 11.9 3768 12.06 666 11.09 1442 11.37 2218 10.88 2994 11.91 3770 12.06 668 11.09 1444 11.36 2220 10.89 2996 11.91 3772 12.07 670 11.09 1446 11.36 2222 10.9 2998 11.9 3774 12.08 672 11.09 1448 11.35 2224 10.91 3000 11.91 3776 12.09 674 11.09 1450 11.35 2226 10.91 3002 11.91 3778 12.1 676 11.09 1452 11.35 2228 10.92 3004 11.91 3780 12.09 678 11.09 1454 11.35 2230 10.92 3006 11.91 3782 12.12 680 11.09 1456 11.35 2232 10.93 3008 11.9 3784 12.13 682 11.09 1458 11.34 2234 10.94 3010 11.91 3786 12.14 684 11.09 1460 11.34 2236 10.94 3012 11.91 3788 12.13 686 11.08 1462 11.33 2238 10.95 3014 11.92 3790 12.14 688 11.08 1464 11.32 2240 10.96 3016 11.92 3792 12.14 690 11.08 1466 11.32 2242 10.96 3018 11.92 3794 12.14 692 11.08 1468 11.32 2244 10.97 3020 11.92 3796 12.15 694 11.07 1470 11.31 2246 10.99 3022 11.92 3798 12.15 696 11.06 1472 11.31 2248 10.99 3024 11.92 3800 12.16 698 11.05 1474 11.3 2250 10.99 3026 11.92 3802 12.16 700 11.04 1476 11.29 2252 10.99 3028 11.91 3804 12.17 702 11.03 1478 11.29 2254 11 3030 11.91 3806 12.17 704 11.02 1480 11.28 2256 11 3032 11.92 3808 12.17 706 11.01 1482 11.28 2258 11 3034 11.91 3810 12.15 AC 25.491-1 10/30/00 708 11 1484 11.28 2260 11.01 3036 11.91 3812 12.14 710 10.99 1486 11.28 2262 11.01 3038 11.91 3814 12.13 712 10.99 1488 11.28 2264 11.02 3040 11.91 3816 12.12 714 10.98 1490 11.27 2266 11.02 3042 11.9 3818 12.11 716 10.99 1492 11.27 2268 11.02 3044 11.9 3820 12.1 718 10.98 1494 11.27 2270 11.04 3046 11.9 3822 12.09 720 10.98 1496 11.26 2272 11.05 3048 11.9 3824 12.09 722 10.98 1498 11.26 2274 11.05 3050 11.9 3826 12.09 724 10.98 1500 11.25 2276 11.06 3052 11.9 3828 12.08 726 10.98 1502 11.25 2278 11.06 3054 11.9 3830 12.07 728 10.98 1504 11.24 2280 11.05 3056 11.9 3832 12.07 730 10.99 1506 11.23 2282 11.04 3058 11.9 3834 12.06 732 10.99 1508 11.22 2284 11.03 3060 11.9 3836 12.05 734 11 1510 11.21 2286 11.03 3062 11.91 3838 12.03 736 11 1512 11.19 2288 11.02 3064 11.92 3840 12.03 738 11 1514 11.18 2290 11.03 3066 11.92 3842 12.02 740 11 1516 11.17 2292 11.03 3068 11.92 3844 12.01 742 11 1518 11.17 2294 11.04 3070 11.93 3846 12.02 744 11.01 1520 11.15 2296 11.05 3072 11.93 3848 12.01 746 11.02 1522 11.13 2298 11.06 3074 11.93 3850 12.01 748 11.02 1524 11.12 2300 11.07 3076 11.93 3852 12.01 750 11.02 1526 11.1 2302 11.09 3078 11.94 3854 12.01 752 11.02 1528 11.1 2304 11.1 3080 11.94 3856 12.02 754 11.02 1530 11.18 2306 11.1 3082 11.95 3858 12.02 756 11.02 1532 11.17 2308 11.11 3084 11.95 3860 12.01 758 11.01 1534 11.14 2310 11.12 3086 11.95 3862 12 760 11.01 1536 11.14 2312 11.14 3088 11.96 3864 12 762 11 1538 11.12 2314 11.14 3090 11.96 3866 11.98 764 11 1540 11 2316 11.15 3092 11.96 3868 11.97 766 11 1542 10.97 2318 11.16 3094 11.96 3870 11.97 768 11 1544 10.95 2320 11.16 3096 11.96 3872 11.96 770 11 1546 10.94 2322 11.16 3098 11.96 3874 11.96 772 11 1548 10.92 2324 11.15 3100 11.95 3876 11.96 774 10.99 1550 10.91 2326 11.15 3102 11.94 3878 11.96 3880 11.95 * The National Aeronautics and Space Administration (NASA) Report CR-119 identifies an elevation of 10.97 inches at 1620 feet. This is considered a typographical error and has been corrected in Table 1. The elevation is 10.87 inches.

10/30/00 AC 25.491-1 TABLE 2 SF28R SEVERE BUMP MODIFICATIONS PER ICAO ANNEX 14, SPECIFICATION 9.4.15 Distance Original Elevation (ft) Modified Elevation (ft) 1530 11.18 11.10 1532 11.17 11.11 1534 11.14 11.11 1536 11.14 11.07 1538 11.12 11.04 /s/ DORENDA D. BAKER Acting Manager, Transport Airplane Directorate, Aircraft Certification Service, ANM-100