CYPRESS, TX, USA
N51593
Maule M-5-210C
The pilot received three separate weather briefings of forecasted IFR conditions in the 6 hours prior to his departure. While flying in instrument meteorological conditions en route to Conroe, Texas, the pilot reported to Houston Approach Control that 'I lost my gyros.' No-gyro vectors were given to the pilot by Houston Approach Control in an attempt to align the airplane for an ILS approach to runway 8 at Houston Intercontinental Airport. The pilot lost control of the airplane and it impacted the ground. The weather conditions at David Wayne Hooks Municipal Airport, which is 10 nautical miles north east of the accident site, at 1850 CST were estimated ceiling 500 feet AGL overcast, visibility 1 mile with fog, temperature of 57 degrees, dew point of 56 degrees with, winds at 070 degrees at 6 knots, and an altimeter setting of 30.17 inches. Examination of the vacuum pump input shaft by NTSB metallurgist revealed that the shaft failed as a result of sudden stoppage of the vacuum pump.
HISTORY OF FLIGHT On November 17, 1995, at 1909 central standard time, a Maule M-5-210C, N51593, was destroyed upon impact with terrain following a loss of control near Cypress, Texas. The instrument rated private pilot was fatally injured. The aircraft was being operated by the owner under Title 14 CFR Part 91. The flight originated from the San Antonio International Airport, near San Antonio, Texas, at 1726, with Conroe, Texas, as its intended destination. Instrument meteorological conditions prevailed for the night cross country flight for which an instrument flight plan was filed. The pilot called the FAA FSS facility for weather briefings three times within the 6 hours preceding his flight. Each time the pilot was informed of forecast instrument meteorological conditions along his proposed route. ATC cleared the pilot to Conroe via V198 to Gland then direct Conroe, with an assigned altitude of 5,000 feet, and the flight departed at 1726. Approximately 1 hour and 38 minutes into the flight, the pilot contacted Houston Approach Control and declared that "I lost my gyros." Houston Approach Control issued the pilot no-gyro vectors to align the airplane for an ILS approach at the Houston Intercontinental Airport. While maneuvering the airplane, the pilot lost control of the aircraft. National Track Analysis Program data and ATC voice recordings revealed that the pilot flew the airplane for 15 to 16 minutes from the onset of his emergency. The wreckage was not located until approximately 0800 the next day, due to the inclement weather in the area. There were no eye witnesses to the accident. PERSONNEL INFORMATION The pilot received an IFR competency check on November 14, 1995. The instructor who gave the check reported to the investigator in charge that he believed the pilot to be "above average" in his knowledge and flight skills. The pilot's log book was not made available to the investigator. AIRCRAFT INFORMATION The aircraft's vacuum pump was replaced with an overhauled pump on August 20, 1986, and the airplane had been flown approximately 425 hours since that installation. The altimeter system was last checked when the aircraft entered service on April 3, 1974, and the last documentation that the VOR's were checked was on March 1, 1975. Evaluation of the aircraft's log books revealed that the transponder system had never been inspected/tested. The pilot reported to San Angelo FSS, while filing an IFR flight plan for this trip, that he had 4 hours of fuel on board. METEOROLOGICAL INFORMATION For the time period of the pilot's flight from San Antonio, Texas, to Conroe, Texas, there were two Airmets. The first one was forecasting icing conditions above 10,000 feet MSL. The second Airmet was for IFR conditions with ceilings occasionally below 1,000 feet AGL, and the visibility below 3 miles with light rain and fog. The preflight briefer at the San Angelo FSS informed the pilot that conditions were generally low IFR with ceilings at or below 500 feet AGL, visibility less then a mile, with rain all along his route of flight. The pilot was provided two special surface aviation weather reports before departure. At 2231 UTC, San Antonio reported a measured ceiling of 800 feet AGL (variable 400 feet AGL to 1100 feet AGL), visibility over 10 miles, temperature of 59 degrees, dew point of 58 degrees, winds were 020 degrees for 3 knots, with a remark that the rain ended at 2157 UTC. At 2242 UTC, Houston Intercontinental Airport reported a measured broken ceiling at 1,200 feet AGL, a 2,400 feet AGL overcast, visibility 3 miles with light rain and fog, winds were reported from 050 degrees at 6 knots, with an altimeter setting of 30.11 inches. Additional weather information was provided to the investigator in charge for David Wayne Hooks Municipal Airport, which is located 10 nautical miles north east of the accident site. At 1850 CST, Hooks was reporting an estimated ceiling of 500 feet AGL overcast, visibility 1 mile with fog, temperature of 57 degrees, dew point of 56 degrees, winds at 070 degrees at 6 knots, and an altimeter setting of 30.17 inches. During this same time period, pilots who were flying the ILS approach to runway 17 at David Wayne Hooks Municipal Airport were reporting that they were not making visual contact with the runway environment until reaching minimums, which would be 200 feet AGL. AIDS TO NAVIGATION The ILS to Montgomery County Airport (the pilot's intended destination), near Conroe, Texas, was out of service. The pilot had been briefed about this ILS being out of service. WRECKAGE AND IMPACT INFORMATION The accident site was located 400 yards south of the 2200 block on Schiel Rd., Cypress, Texas (270 degree radial and 21 nautical miles from the Humble VORTAC). The airplane came to rest in a freshly plowed corn field on a measured magnetic heading of 240 degrees in a vertical orientation. The airplane's engine was found buried in the ground so that only one of the magnetos was visible. The leading edge of both wings were resting on the ground and compressed aft. Both propeller blades were separated from the hub. No significant blade leading edge damage was found on either blade. All aircraft components were located within a 30 foot radius of the impact point of the airplane. Flight control continuity could not be established due to aircraft impact damage. Examination of the airframe at the accident site did not disclose any mechanical problems. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed by the Office of the Medical Examiner of Harris County at Houston, Texas, on November 18, 1995. Toxicological testing was not performed due to a lack of suitable specimens. TEST AND RESEARCH Further examination of the engine on November 29, 1995, revealed that the vacuum pump input shaft was separated. The vacuum pump input shaft was examined by the National Transportation Safety Board's Materials Laboratory Division in Washington, D.C. Their report indicates that "the direction of torsional loading resulting in the separation was as if the input end of the shaft rotated clockwise relative to the portion that remained in the pump." ADDITIONAL DATA The airplane was released to the owner's representative upon completion of the investigation.
The pilot's failure to maintain aircraft control while flying in instrument meteorological conditions. Factors were the weather, and the failure of the airplane's vacuum pump which rendered the attitude indicator and the directional gyro inoperative.
Source: NTSB Aviation Accident Database
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