ROCHESTER, NY, USA
N853CA
Beech 1900D
When the landing gear handle was selected to the down position in preparation for landing, the landing gear would not extend electrically. The flightcrew executed an abnormal checklist, which included utilizing a mechanical hydraulic pump; however, the landing gear remained retracted. The flightcrew elected to land the airplane with the gear retracted. Examination of the landing gear system revealed that maintenance personnel had improperly installed the landing gear service valve 6 days prior, by reversing two hydraulic lines. Reasons for the electrical malfunction of the landing gear service valve could not be determined. The airplane's maintenance manual did not refer to the cycling of the landing gear, mechanically or electrically, after replacement of the landing gear service valve.
On June 3, 2000, about 1557 eastern daylight time, a Beech 1900D, N853CA, operated by CommutAir and doing business as US Airways Express flight 4519, sustained minor damage during a gear up landing at the Greater Rochester International Airport (ROC), Rochester, New York. The certificated airline transport pilot, commercial co-pilot, and 11 passengers, were not injured. Visual meteorological conditions prevailed and an instrument flight rules flight plan was filed for the scheduled passenger flight conducted under 14 CFR Part 121. The flight had originated from the Washington Dulles International Airport (IAD), Dulles, Virginia. According to the pilot, the flight departed from IAD and the landing gear was retracted normally. When the landing gear handle was selected to the down position in preparation for landing at ROC, the landing gear would not extend. After the crew executed the abnormal checklist, the landing gear still remained retracted. The flight crew made two approaches to the airport and then departed the area to communicate with company maintenance and to evaluate the situation. A decision was made to land with the gear retracted and the airplane proceeded back to ROC. The airplane touched down with the belly of the fuselage on Runway 04, a 6,300-foot long asphalt runway, and skidded to a stop. After the incident, when the airplane was raised off of the runway by a crane, the landing gear did not "free fall." Unsuccessful attempts to lower the landing gear were made by placing the landing gear selector handle in the "down" position and by using the alternate extension handle. When hydraulic pressure was removed from the landing gear system, the landing gear extended and locked. Testing of the landing gear system was conducted after the airplane was removed from the runway. The landing gear service valve was replaced and the landing gear was cycled using the landing gear selector handle. An attempt to extend the landing gear by the alternate extension handle was unsuccessful. A second landing gear service valve was installed, and after re-tracing the hydraulic lines, the hydraulic return line and the pump pressure line positions were switched at the valve ports. The landing gear was then cycled successfully using the landing gear selector handle and by utilizing the alternate extension handle. According to the Raytheon Aircraft Beech 1900D Airliner Maintenance Manual, dated March 28, 1997, a landing gear service valve, which was located in the left inboard wing section of the airplane, was used in conjunction with the hand pump to raise and lower the landing gear for maintenance purposes. Four hydraulic plumbing tube assemblies were connected through ports located on each side of the valve. On the forward facing side of the valve were the "retract port" and the "emergency extend port." On the aft facing side of the valve were the "hand pump pressure port" and the "return port," which included a check valve installed between the tube and port. The hydraulic plumbing tube assemblies were also color coded, with the "retract port" receiving a blue marked line, the "emergency extend port" receiving a light green marked line, the "hand pump pressure port" receiving a yellow marked line, and the "return port" receiving a orange marked line. According to maintenance records, on May 28, 2000, airline maintenance personnel had replaced the landing gear service valve in the airplane after the landing gear failed to extend and the crew had to manually pump the landing gear down. Upon completion of the valve installation, maintenance personnel performed a "normal gear extension and retraction using the aircraft electrical system." The Raytheon Aircraft Beech 1900D Airliner Maintenance Manual, dated March 24, 2000, did not refer to the cycling of the landing gear, mechanically or electrically, after replacement of the landing gear service valve. In a letter composed by the operator, addressed to the airplane manufacturer, it stated; "We have concluded that the lines to and from the service valve may have been reversed on installation, thereby precluding successful manual extension. The 'handpump pressure tube' and the 'pressure tube' can be reversed inadvertently." The landing gear service valve replaced on May 28, 2000, and the two service valves replaced on June 3, 2000, were retained for further examination. On June 12, 2000, the three service valves were x-rayed using a Triplett and Barton x-ray machine and a Phillips MCRS 2000 real time x-ray machine, in the presence of a Federal Aviation Administration inspector, at the Raytheon Aircraft Company, Wichita, Kansas. No defects or blockages were observed. The valves were then forwarded to Airight Products, Inc., Wichita, Kansas, the same day, for examination in the presence of the FAA inspector. External examination of the valves did not reveal any anomalies. A functional test of all three valves electrical system was performed. The valves were attached to an electrical test box and power was applied. The plunger handle on each valve was cycled several times between the up and down positions. Both micro switches on the valves were found operational. A functional test of all three valves hydraulic system was performed. To conduct the test, a test bench hand pump was utilized to apply low pressure to the valve's hand pump port. With the plunger handle in the down position, hydraulic fluid flow was observed coming from the gear down port of the valve. The plunger handle was then moved to the up position, and fluid was observed coming from the gear up port of the valve. The gear down port was then capped off, and 50 PSI of pressure was applied to the valve using the hand pump. No fluid was observed coming from either the gear up port or return port. The test bench hydraulic pump was then attached to the hand pump port of the valve, and the gear up and gear down ports, were capped off. A pressure of 1,500 PSI was applied to the valve, and no leakage of fluid was observed from the return port while the plunger handle was in the up or down position. All ports were then opened, and the test bench hydraulic pump was connected to the gear up port, in order to confirm the operation of its check valve. A pressure of 1,500 PSI was applied, and no leakage of fluid was observed. All functional tests of the valves were satisfactory, and no discrepancies were noted. According to the airplane operator, a change was made to the General Maintenance Manual for the Beech 1900D, on June 15, 2000, which included additional guidance when installing a new service valve. The manual changes stated, "If installing a new Service Valve. Install the Check Valve in the Bleed Air Return Port of the Service Valve, taking note to the direction of flow." An additional change was "Cycle Landing gear with the Power Pack Electrically and Manually with Hand Pump before removing the airplane from the jacks."
The reversal of landing gear hydraulic lines by company maintenance personnel. Factors related to the incident were the manufacturers omission of maintenance procedures, and the failure of an electrical switch for undetermined reasons.
Source: NTSB Aviation Accident Database
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