Narrative:
The Capital Airlines Viscount took off from Detroit-Willow Run Airport at 07:00 CST for a flight to Chicago-Midway. The flight had been uneventful when the aircraft approached Chicago, making a right hand turn to finals for a landing on runway 31R. When over the boundary of the airport the captain reduced power and called for 47deg flaps. As the first officer moved the flap control to 47deg, he felt the aircraft decelerate and settle. Glancing at the instrument panel, he noticed 3 of the 4 17-degree pitch lights were illuminated. These lights illuminate when the propeller blades are at a 17deg pitch or below; 21 degrees is normally the minimum in-flight blade angle. Knowing this was an abnormal situation he chose to apply power. Advancing power caused the propellers to immediately seek the lowest possible angle. When the throttles were 3/4 fully forward the aircraft sank quickly, touching down on the east taxiway, 414 feet short of the runway threshold. The aircraft skidded onto the runway on its belly coming to rest 1626 feet past the point of first touchdown.
It appeared that at least two microswitches had failed, permitting the energizing of the 21-degree pitch lock solenoid. This made it possible for the stops to be withdrawn during the approach. As the crew didn't see the 21-degree pitch lock solenoid warning light, the emergency switch preventing the propellers from going into ground fine pitch range while in flight, was not actuated.
The hull was used to build Vickers 757 Viscount c/n 301 which entered service with Trans Canada Air Lines May 1957.
PROBABLE CAUSE: "A malfunctioning of the propeller control switches which culminated in an abrupt loss of lift."
Loss of control
accident date: 20-02-1956
type: Vickers 744 Viscount
registration: N7404
| Status: | Accident investigation report completed and information captured |
| Date: | Monday 20 February 1956 |
| Time: | 08:11 |
| Type: |  Vickers 744 Viscount |
| Operator: | Capital Airlines |
| Registration: | N7404 |
| MSN: | 90 |
| First flight: | 1955 |
| Crew: | Fatalities: 0 / Occupants: 5 |
| Passengers: | Fatalities: 0 / Occupants: 37 |
| Total: | Fatalities: 0 / Occupants: 42 |
| Aircraft damage: | Damaged beyond repair |
| Location: | Chicago-Midway Airport, IL (MDW) ( United States of America)
|
| Phase: | Landing (LDG) |
| Nature: | Domestic Scheduled Passenger |
| Departure airport: | Detroit-Willow Run Airport, MI (YIP/KYIP), United States of America |
| Chicago-Midway Airport, IL (MDW/KMDW), United States of America |
The Capital Airlines Viscount took off from Detroit-Willow Run Airport at 07:00 CST for a flight to Chicago-Midway. The flight had been uneventful when the aircraft approached Chicago, making a right hand turn to finals for a landing on runway 31R. When over the boundary of the airport the captain reduced power and called for 47deg flaps. As the first officer moved the flap control to 47deg, he felt the aircraft decelerate and settle. Glancing at the instrument panel, he noticed 3 of the 4 17-degree pitch lights were illuminated. These lights illuminate when the propeller blades are at a 17deg pitch or below; 21 degrees is normally the minimum in-flight blade angle. Knowing this was an abnormal situation he chose to apply power. Advancing power caused the propellers to immediately seek the lowest possible angle. When the throttles were 3/4 fully forward the aircraft sank quickly, touching down on the east taxiway, 414 feet short of the runway threshold. The aircraft skidded onto the runway on its belly coming to rest 1626 feet past the point of first touchdown.
It appeared that at least two microswitches had failed, permitting the energizing of the 21-degree pitch lock solenoid. This made it possible for the stops to be withdrawn during the approach. As the crew didn't see the 21-degree pitch lock solenoid warning light, the emergency switch preventing the propellers from going into ground fine pitch range while in flight, was not actuated.
The hull was used to build Vickers 757 Viscount c/n 301 which entered service with Trans Canada Air Lines May 1957.
Probable Cause:
PROBABLE CAUSE: "A malfunctioning of the propeller control switches which culminated in an abrupt loss of lift."
Classification:
Engine reverse issueLoss of control
Sources:
» ICAO Accident Digest No.8, Circular 54-AN/49 (51-55)Photos
accident date: 20-02-1956
type: Vickers 744 Viscount
registration: N7404
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Detroit-Willow Run Airport, MI to Chicago-Midway Airport, IL as the crow flies is 350 km (219 miles).
Distance from Detroit-Willow Run Airport, MI to Chicago-Midway Airport, IL as the crow flies is 350 km (219 miles).
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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