FA-65846 / Aviation weight and balance / Open access

Avgas and jet fuel densities transposed · case 01

Fuel weight is overstated for avgas aircraft and understated for diesel-converted aircraft.

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ROOT CAUSE

The density table maps 100LL to the jet fuel figure and JETA to the avgas figure.

VERIFIED REPAIR

Map 100LL to 6.0 lb/gal and JETA to 6.7 lb/gal.

Unsuccessful approach: Using the avgas density for every grade fixes piston aircraft but still underweights jet fuel loads.

Case contract

Input {'empty':[lb,in],'items':[[name,lb,in]],'fuel_gal','fuel_arm','fuel_type'}; fuel density 6.0 lb/gal for 100LL and 6.7 for JETA, other grades return 'ERR_FUEL_TYPE'; negative item weights are removals at that arm; return [total lb, total lb-in, CG in] rounded 1/1/2.

Why this case matters

Loaded-aircraft CG is the sum of station moments divided by total weight; every station, including the empty aircraft and fuel, must contribute both weight and moment.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    dens = {'100LL': 6.7, 'JETA': 6.0}
    if x['fuel_type'] not in dens: return 'ERR_FUEL_TYPE'
    ew, ea = x['empty']
    w = ew
    m = ew * ea
    for name, iw, ia in x['items']:
        w += iw
        m += iw * ia
    fw = x['fuel_gal'] * dens[x['fuel_type']]
    w += fw
    m += fw * x['fuel_arm']
    cg = m / w
    return [round(w, 1), round(m, 1), round(cg, 2)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 171.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 45.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2386.0, 101482.0, 42.53]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 21.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2040.7, 82385.6, 40.37]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 61.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2043.0, 83176.0, 40.71]], ['zero fuel ferry check', {'empty': [1510.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1510.0, 58135.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 10.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1750.5, 41.7], 'items': [['st0', -61.9, 71.4], ['st1', 81.5, 64.2], ['st2', -41.5, 55.2], ['st3', 103.0, 80.5], ['st4', 173.7, 46.3]], 'fuel_gal': 12.5, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2089.1, 91871.5, 43.98]], ['sampled case 2', {'empty': [1408.8, 40.0], 'items': [['st0', 205.1, 51.5], ['st1', 170.5, 96.0], ['st2', 41.8, 41.2]], 'fuel_gal': 42.9, 'fuel_arm': 47.0, 'fuel_type': 'JETA'}, [2113.6, 98514.0, 46.61]], ['sampled case 3', {'empty': [1517.4, 36.7], 'items': [], 'fuel_gal': 20.3, 'fuel_arm': 48.8, 'fuel_type': '100LL'}, [1639.2, 61632.4, 37.6]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 172.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 50.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2392.0, 101994.0, 42.64]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 22.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2047.4, 82707.2, 40.4]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 62.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2044.0, 83256.0, 40.73]], ['zero fuel ferry check', {'empty': [1520.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1520.0, 58520.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 20.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1464.4, 41.7], 'items': [['st0', 205.5, 74.6], ['st1', -137.9, 94.7], ['st2', -78.1, 107.4], ['st3', 7.4, 81.9], ['st4', 48.8, 73.0]], 'fuel_gal': 39.2, 'fuel_arm': 45.3, 'fuel_type': '100LL'}, [1745.3, 69771.7, 39.98]], ['sampled case 2', {'empty': [1609.7, 41.4], 'items': [['st0', 37.0, 68.4], ['st1', 210.3, 87.2]], 'fuel_gal': 9.1, 'fuel_arm': 49.5, 'fuel_type': 'JETA'}, [1918.0, 90528.6, 47.2]], ['sampled case 3', {'empty': [1748.1, 40.4], 'items': [['st0', 142.1, 66.6], ['st1', 114.2, 115.9], ['st2', 214.0, 53.3], ['st3', -210.5, 58.6]], 'fuel_gal': 56.2, 'fuel_arm': 46.6, 'fuel_type': '100LL'}, [2345.1, 108107.3, 46.1]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 173.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 55.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2398.0, 102506.0, 42.75]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 23.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2054.1, 83028.8, 40.42]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 63.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2045.0, 83336.0, 40.75]], ['zero fuel ferry check', {'empty': [1530.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1530.0, 58905.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1793.8, 36.7], 'items': [], 'fuel_gal': 47.3, 'fuel_arm': 49.2, 'fuel_type': '100LL'}, [2077.6, 79795.4, 38.41]], ['sampled case 2', {'empty': [1887.8, 37.9], 'items': [['st0', 210.1, 118.7], ['st1', 160.5, 39.3], ['st2', 183.9, 81.3], ['st3', 75.5, 51.6]], 'fuel_gal': 29.0, 'fuel_arm': 48.1, 'fuel_type': '100LL'}, [2691.8, 130010.4, 48.3]], ['sampled case 3', {'empty': [1787.9, 37.7], 'items': [['st0', 26.8, 31.1], ['st1', -138.4, 66.2], ['st2', 96.1, 66.7], ['st3', 86.1, 100.9], ['st4', 40.8, 92.5]], 'fuel_gal': 44.1, 'fuel_arm': 48.5, 'fuel_type': '100LL'}, [2163.9, 90779.7, 41.95]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 174.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 60.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2404.0, 103018.0, 42.85]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 24.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2060.8, 83350.4, 40.45]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 64.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2046.0, 83416.0, 40.77]], ['zero fuel ferry check', {'empty': [1540.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1540.0, 59290.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1894.8, 39.9], 'items': [['st0', 16.4, 61.4], ['st1', 169.2, 77.5], ['st2', 185.9, 31.1], ['st3', -205.6, 115.1]], 'fuel_gal': 3.1, 'fuel_arm': 49.7, 'fuel_type': '100LL'}, [2079.3, 72763.8, 34.99]], ['sampled case 2', {'empty': [1972.5, 36.6], 'items': [], 'fuel_gal': 22.2, 'fuel_arm': 47.9, 'fuel_type': 'JETA'}, [2121.2, 79318.1, 37.39]], ['sampled case 3', {'empty': [1953.0, 37.4], 'items': [['st0', 15.5, 119.0], ['st1', 86.7, 76.1], ['st2', 189.4, 96.4]], 'fuel_gal': 53.7, 'fuel_arm': 49.2, 'fuel_type': '100LL'}, [2566.8, 115595.0, 45.03]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 175.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 65.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2410.0, 103530.0, 42.96]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 25.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2067.5, 83672.0, 40.47]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 65.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2047.0, 83496.0, 40.79]], ['zero fuel ferry check', {'empty': [1550.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1550.0, 59675.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 50.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1931.2, 41.1], 'items': [], 'fuel_gal': 38.2, 'fuel_arm': 45.5, 'fuel_type': '100LL'}, [2160.4, 89800.9, 41.57]], ['sampled case 2', {'empty': [1766.5, 40.9], 'items': [['st0', -27.8, 60.1], ['st1', 183.8, 57.4], ['st2', 133.5, 84.7], ['st3', 87.9, 53.2], ['st4', -91.2, 76.1]], 'fuel_gal': 53.4, 'fuel_arm': 49.4, 'fuel_type': '100LL'}, [2373.1, 106000.4, 44.67]], ['sampled case 3', {'empty': [1875.6, 41.2], 'items': [['st0', 162.6, 70.4], ['st1', 185.1, 108.0]], 'fuel_gal': 22.0, 'fuel_arm': 47.1, 'fuel_type': 'JETA'}, [2370.7, 115655.1, 48.79]]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
four-seat normal load	`[2414.0, 102826.0, 42.6]`	`[2386.0, 101482.0, 42.53]`	Failed
jet-A diesel conversion	`[2026.0, 81680.0, 40.32]`	`[2040.7, 82385.6, 40.37]`	Failed
removed seat entry	`[2064.0, 84184.0, 40.79]`	`[2043.0, 83176.0, 40.71]`	Failed
zero fuel ferry check	`[1510.0, 58135.0, 38.5]`	`[1510.0, 58135.0, 38.5]`	Passed
unknown fuel grade	`ERR_FUEL_TYPE`	`ERR_FUEL_TYPE`	Passed
sampled case 1	`[2080.3, 91451.5, 43.96]`	`[2089.1, 91871.5, 43.98]`	Failed
sampled case 2	`[2083.6, 97102.6, 46.6]`	`[2113.6, 98514.0, 46.61]`	Failed
sampled case 3	`[1653.4, 62325.9, 37.7]`	`[1639.2, 61632.4, 37.6]`	Failed

SHA-256 / 0e110dc0c2c735981e0ded309cdd900c8b0b4d9e22778229c116fa4a8ed40393

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    dens = {'100LL': 6.0, 'JETA': 6.0}
    if x['fuel_type'] not in dens: return 'ERR_FUEL_TYPE'
    ew, ea = x['empty']
    w = ew
    m = ew * ea
    for name, iw, ia in x['items']:
        w += iw
        m += iw * ia
    fw = x['fuel_gal'] * dens[x['fuel_type']]
    w += fw
    m += fw * x['fuel_arm']
    cg = m / w
    return [round(w, 1), round(m, 1), round(cg, 2)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 171.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 45.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2386.0, 101482.0, 42.53]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 21.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2040.7, 82385.6, 40.37]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 61.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2043.0, 83176.0, 40.71]], ['zero fuel ferry check', {'empty': [1510.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1510.0, 58135.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 10.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1750.5, 41.7], 'items': [['st0', -61.9, 71.4], ['st1', 81.5, 64.2], ['st2', -41.5, 55.2], ['st3', 103.0, 80.5], ['st4', 173.7, 46.3]], 'fuel_gal': 12.5, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2089.1, 91871.5, 43.98]], ['sampled case 2', {'empty': [1408.8, 40.0], 'items': [['st0', 205.1, 51.5], ['st1', 170.5, 96.0], ['st2', 41.8, 41.2]], 'fuel_gal': 42.9, 'fuel_arm': 47.0, 'fuel_type': 'JETA'}, [2113.6, 98514.0, 46.61]], ['sampled case 3', {'empty': [1517.4, 36.7], 'items': [], 'fuel_gal': 20.3, 'fuel_arm': 48.8, 'fuel_type': '100LL'}, [1639.2, 61632.4, 37.6]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 172.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 50.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2392.0, 101994.0, 42.64]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 22.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2047.4, 82707.2, 40.4]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 62.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2044.0, 83256.0, 40.73]], ['zero fuel ferry check', {'empty': [1520.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1520.0, 58520.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 20.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1464.4, 41.7], 'items': [['st0', 205.5, 74.6], ['st1', -137.9, 94.7], ['st2', -78.1, 107.4], ['st3', 7.4, 81.9], ['st4', 48.8, 73.0]], 'fuel_gal': 39.2, 'fuel_arm': 45.3, 'fuel_type': '100LL'}, [1745.3, 69771.7, 39.98]], ['sampled case 2', {'empty': [1609.7, 41.4], 'items': [['st0', 37.0, 68.4], ['st1', 210.3, 87.2]], 'fuel_gal': 9.1, 'fuel_arm': 49.5, 'fuel_type': 'JETA'}, [1918.0, 90528.6, 47.2]], ['sampled case 3', {'empty': [1748.1, 40.4], 'items': [['st0', 142.1, 66.6], ['st1', 114.2, 115.9], ['st2', 214.0, 53.3], ['st3', -210.5, 58.6]], 'fuel_gal': 56.2, 'fuel_arm': 46.6, 'fuel_type': '100LL'}, [2345.1, 108107.3, 46.1]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 173.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 55.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2398.0, 102506.0, 42.75]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 23.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2054.1, 83028.8, 40.42]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 63.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2045.0, 83336.0, 40.75]], ['zero fuel ferry check', {'empty': [1530.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1530.0, 58905.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1793.8, 36.7], 'items': [], 'fuel_gal': 47.3, 'fuel_arm': 49.2, 'fuel_type': '100LL'}, [2077.6, 79795.4, 38.41]], ['sampled case 2', {'empty': [1887.8, 37.9], 'items': [['st0', 210.1, 118.7], ['st1', 160.5, 39.3], ['st2', 183.9, 81.3], ['st3', 75.5, 51.6]], 'fuel_gal': 29.0, 'fuel_arm': 48.1, 'fuel_type': '100LL'}, [2691.8, 130010.4, 48.3]], ['sampled case 3', {'empty': [1787.9, 37.7], 'items': [['st0', 26.8, 31.1], ['st1', -138.4, 66.2], ['st2', 96.1, 66.7], ['st3', 86.1, 100.9], ['st4', 40.8, 92.5]], 'fuel_gal': 44.1, 'fuel_arm': 48.5, 'fuel_type': '100LL'}, [2163.9, 90779.7, 41.95]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 174.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 60.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2404.0, 103018.0, 42.85]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 24.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2060.8, 83350.4, 40.45]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 64.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2046.0, 83416.0, 40.77]], ['zero fuel ferry check', {'empty': [1540.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1540.0, 59290.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1894.8, 39.9], 'items': [['st0', 16.4, 61.4], ['st1', 169.2, 77.5], ['st2', 185.9, 31.1], ['st3', -205.6, 115.1]], 'fuel_gal': 3.1, 'fuel_arm': 49.7, 'fuel_type': '100LL'}, [2079.3, 72763.8, 34.99]], ['sampled case 2', {'empty': [1972.5, 36.6], 'items': [], 'fuel_gal': 22.2, 'fuel_arm': 47.9, 'fuel_type': 'JETA'}, [2121.2, 79318.1, 37.39]], ['sampled case 3', {'empty': [1953.0, 37.4], 'items': [['st0', 15.5, 119.0], ['st1', 86.7, 76.1], ['st2', 189.4, 96.4]], 'fuel_gal': 53.7, 'fuel_arm': 49.2, 'fuel_type': '100LL'}, [2566.8, 115595.0, 45.03]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 175.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 65.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2410.0, 103530.0, 42.96]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 25.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2067.5, 83672.0, 40.47]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 65.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2047.0, 83496.0, 40.79]], ['zero fuel ferry check', {'empty': [1550.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1550.0, 59675.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 50.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1931.2, 41.1], 'items': [], 'fuel_gal': 38.2, 'fuel_arm': 45.5, 'fuel_type': '100LL'}, [2160.4, 89800.9, 41.57]], ['sampled case 2', {'empty': [1766.5, 40.9], 'items': [['st0', -27.8, 60.1], ['st1', 183.8, 57.4], ['st2', 133.5, 84.7], ['st3', 87.9, 53.2], ['st4', -91.2, 76.1]], 'fuel_gal': 53.4, 'fuel_arm': 49.4, 'fuel_type': '100LL'}, [2373.1, 106000.4, 44.67]], ['sampled case 3', {'empty': [1875.6, 41.2], 'items': [['st0', 162.6, 70.4], ['st1', 185.1, 108.0]], 'fuel_gal': 22.0, 'fuel_arm': 47.1, 'fuel_type': 'JETA'}, [2370.7, 115655.1, 48.79]]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
four-seat normal load	`[2386.0, 101482.0, 42.53]`	`[2386.0, 101482.0, 42.53]`	Passed
jet-A diesel conversion	`[2026.0, 81680.0, 40.32]`	`[2040.7, 82385.6, 40.37]`	Failed
removed seat entry	`[2043.0, 83176.0, 40.71]`	`[2043.0, 83176.0, 40.71]`	Passed
zero fuel ferry check	`[1510.0, 58135.0, 38.5]`	`[1510.0, 58135.0, 38.5]`	Passed
unknown fuel grade	`ERR_FUEL_TYPE`	`ERR_FUEL_TYPE`	Passed
sampled case 1	`[2080.3, 91451.5, 43.96]`	`[2089.1, 91871.5, 43.98]`	Failed
sampled case 2	`[2083.6, 97102.6, 46.6]`	`[2113.6, 98514.0, 46.61]`	Failed
sampled case 3	`[1639.2, 61632.4, 37.6]`	`[1639.2, 61632.4, 37.6]`	Passed

SHA-256 / c71c5a57e867ab3e0559f9b13f46186eef050f89c62e31ee54afb2d78623a6f4

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    dens = {'100LL': 6.0, 'JETA': 6.7}
    if x['fuel_type'] not in dens: return 'ERR_FUEL_TYPE'
    ew, ea = x['empty']
    w = ew
    m = ew * ea
    for name, iw, ia in x['items']:
        w += iw
        m += iw * ia
    fw = x['fuel_gal'] * dens[x['fuel_type']]
    w += fw
    m += fw * x['fuel_arm']
    cg = m / w
    return [round(w, 1), round(m, 1), round(cg, 2)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 171.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 45.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2386.0, 101482.0, 42.53]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 21.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2040.7, 82385.6, 40.37]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 61.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2043.0, 83176.0, 40.71]], ['zero fuel ferry check', {'empty': [1510.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1510.0, 58135.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 10.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1750.5, 41.7], 'items': [['st0', -61.9, 71.4], ['st1', 81.5, 64.2], ['st2', -41.5, 55.2], ['st3', 103.0, 80.5], ['st4', 173.7, 46.3]], 'fuel_gal': 12.5, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2089.1, 91871.5, 43.98]], ['sampled case 2', {'empty': [1408.8, 40.0], 'items': [['st0', 205.1, 51.5], ['st1', 170.5, 96.0], ['st2', 41.8, 41.2]], 'fuel_gal': 42.9, 'fuel_arm': 47.0, 'fuel_type': 'JETA'}, [2113.6, 98514.0, 46.61]], ['sampled case 3', {'empty': [1517.4, 36.7], 'items': [], 'fuel_gal': 20.3, 'fuel_arm': 48.8, 'fuel_type': '100LL'}, [1639.2, 61632.4, 37.6]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 172.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 50.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2392.0, 101994.0, 42.64]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 22.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2047.4, 82707.2, 40.4]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 62.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2044.0, 83256.0, 40.73]], ['zero fuel ferry check', {'empty': [1520.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1520.0, 58520.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 20.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1464.4, 41.7], 'items': [['st0', 205.5, 74.6], ['st1', -137.9, 94.7], ['st2', -78.1, 107.4], ['st3', 7.4, 81.9], ['st4', 48.8, 73.0]], 'fuel_gal': 39.2, 'fuel_arm': 45.3, 'fuel_type': '100LL'}, [1745.3, 69771.7, 39.98]], ['sampled case 2', {'empty': [1609.7, 41.4], 'items': [['st0', 37.0, 68.4], ['st1', 210.3, 87.2]], 'fuel_gal': 9.1, 'fuel_arm': 49.5, 'fuel_type': 'JETA'}, [1918.0, 90528.6, 47.2]], ['sampled case 3', {'empty': [1748.1, 40.4], 'items': [['st0', 142.1, 66.6], ['st1', 114.2, 115.9], ['st2', 214.0, 53.3], ['st3', -210.5, 58.6]], 'fuel_gal': 56.2, 'fuel_arm': 46.6, 'fuel_type': '100LL'}, [2345.1, 108107.3, 46.1]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 173.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 55.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2398.0, 102506.0, 42.75]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 23.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2054.1, 83028.8, 40.42]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 63.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2045.0, 83336.0, 40.75]], ['zero fuel ferry check', {'empty': [1530.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1530.0, 58905.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1793.8, 36.7], 'items': [], 'fuel_gal': 47.3, 'fuel_arm': 49.2, 'fuel_type': '100LL'}, [2077.6, 79795.4, 38.41]], ['sampled case 2', {'empty': [1887.8, 37.9], 'items': [['st0', 210.1, 118.7], ['st1', 160.5, 39.3], ['st2', 183.9, 81.3], ['st3', 75.5, 51.6]], 'fuel_gal': 29.0, 'fuel_arm': 48.1, 'fuel_type': '100LL'}, [2691.8, 130010.4, 48.3]], ['sampled case 3', {'empty': [1787.9, 37.7], 'items': [['st0', 26.8, 31.1], ['st1', -138.4, 66.2], ['st2', 96.1, 66.7], ['st3', 86.1, 100.9], ['st4', 40.8, 92.5]], 'fuel_gal': 44.1, 'fuel_arm': 48.5, 'fuel_type': '100LL'}, [2163.9, 90779.7, 41.95]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 174.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 60.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2404.0, 103018.0, 42.85]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 24.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2060.8, 83350.4, 40.45]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 64.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2046.0, 83416.0, 40.77]], ['zero fuel ferry check', {'empty': [1540.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1540.0, 59290.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1894.8, 39.9], 'items': [['st0', 16.4, 61.4], ['st1', 169.2, 77.5], ['st2', 185.9, 31.1], ['st3', -205.6, 115.1]], 'fuel_gal': 3.1, 'fuel_arm': 49.7, 'fuel_type': '100LL'}, [2079.3, 72763.8, 34.99]], ['sampled case 2', {'empty': [1972.5, 36.6], 'items': [], 'fuel_gal': 22.2, 'fuel_arm': 47.9, 'fuel_type': 'JETA'}, [2121.2, 79318.1, 37.39]], ['sampled case 3', {'empty': [1953.0, 37.4], 'items': [['st0', 15.5, 119.0], ['st1', 86.7, 76.1], ['st2', 189.4, 96.4]], 'fuel_gal': 53.7, 'fuel_arm': 49.2, 'fuel_type': '100LL'}, [2566.8, 115595.0, 45.03]]], [['four-seat normal load', {'empty': [1650.0, 39.2], 'items': [['pilot', 175.0, 37.0], ['front pax', 160.0, 37.0], ['rear pax', 120.0, 73.0], ['baggage', 65.0, 95.0]], 'fuel_gal': 40.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2410.0, 103530.0, 42.96]], ['jet-A diesel conversion', {'empty': [1720.0, 40.1], 'items': [['pilot', 180.0, 37.0]], 'fuel_gal': 25.0, 'fuel_arm': 48.0, 'fuel_type': 'JETA'}, [2067.5, 83672.0, 40.47]], ['removed seat entry', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0], ['rear seat removed', -18.0, 73.0], ['cargo', 65.0, 80.0]], 'fuel_gal': 30.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [2047.0, 83496.0, 40.79]], ['zero fuel ferry check', {'empty': [1550.0, 38.5], 'items': [], 'fuel_gal': 0.0, 'fuel_arm': 48.0, 'fuel_type': '100LL'}, [1550.0, 59675.0, 38.5]], ['unknown fuel grade', {'empty': [1650.0, 39.2], 'items': [['pilot', 170.0, 37.0]], 'fuel_gal': 50.0, 'fuel_arm': 48.0, 'fuel_type': 'MOGAS'}, 'ERR_FUEL_TYPE'], ['sampled case 1', {'empty': [1931.2, 41.1], 'items': [], 'fuel_gal': 38.2, 'fuel_arm': 45.5, 'fuel_type': '100LL'}, [2160.4, 89800.9, 41.57]], ['sampled case 2', {'empty': [1766.5, 40.9], 'items': [['st0', -27.8, 60.1], ['st1', 183.8, 57.4], ['st2', 133.5, 84.7], ['st3', 87.9, 53.2], ['st4', -91.2, 76.1]], 'fuel_gal': 53.4, 'fuel_arm': 49.4, 'fuel_type': '100LL'}, [2373.1, 106000.4, 44.67]], ['sampled case 3', {'empty': [1875.6, 41.2], 'items': [['st0', 162.6, 70.4], ['st1', 185.1, 108.0]], 'fuel_gal': 22.0, 'fuel_arm': 47.1, 'fuel_type': 'JETA'}, [2370.7, 115655.1, 48.79]]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
four-seat normal load	`[2386.0, 101482.0, 42.53]`	`[2386.0, 101482.0, 42.53]`	Passed
jet-A diesel conversion	`[2040.7, 82385.6, 40.37]`	`[2040.7, 82385.6, 40.37]`	Passed
removed seat entry	`[2043.0, 83176.0, 40.71]`	`[2043.0, 83176.0, 40.71]`	Passed
zero fuel ferry check	`[1510.0, 58135.0, 38.5]`	`[1510.0, 58135.0, 38.5]`	Passed
unknown fuel grade	`ERR_FUEL_TYPE`	`ERR_FUEL_TYPE`	Passed
sampled case 1	`[2089.1, 91871.5, 43.98]`	`[2089.1, 91871.5, 43.98]`	Passed
sampled case 2	`[2113.6, 98514.0, 46.61]`	`[2113.6, 98514.0, 46.61]`	Passed
sampled case 3	`[1639.2, 61632.4, 37.6]`	`[1639.2, 61632.4, 37.6]`	Passed

SHA-256 / 01a0e70ffa8e5e159c00c562f309dedb36d822b23c5fd17c94d3a13bee87fa88

Verification & scope

A deterministic toy loading model with stipulated constants; it is not an approved aircraft flight manual procedure and makes no claim of regulatory conformance. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:47:37.870874+00:00.

Case digest / 949f4ec8a07d5e9490a4ca075c5ea41e62db4302c834b61024aa21ef7abb72a3