Bombardier Aerospace Flight 388

Bombardier Aerospace Flight 388
	An Air Canada CRJ-100
Accident summary
Accident type	Loss of control through deep stall
place	Byers , Kansas
date	July 26, 1993
Fatalities	3
Survivors	0
Aircraft
Aircraft type	Bombardier CRJ100
operator	Bombardier Aerospace
Mark	C-FCRJ
Departure airport	Wichita Mid-Continent Airport
Destination airport	Wichita Mid-Continent Airport
Passengers	0
crew	3
	Lists of aviation accidents

On July 26, 1993, a Bombardier CRJ-100 crashed during Bombardier Aerospace Flight 388 near Byers , Kansas , carried out for testing purposes by the manufacturer Bombardier Aerospace , killing all three occupants. It was the first fatal accident involving a CRJ100, as well as the first with a total loss of the aircraft.

plane

The plane was a two year old Canadair CL-600-2B19 Regional Jet CRJ100 , which with two turbofan engines of the type General Electric CF34-3A1 was appointed and the first flight was completed on May 10, the 1,991th This was also the maiden flight of a CRJ100.

General

Bombardier Aerospace Flight 388 was part of a test flight program (Canadair report number: RAG-601R-106), which was used to repeat all sections of the certification test. After the end of the test program, Canadair intended to submit the data to Transport Canada in order to obtain type certification . The test flight included the evaluation of a new landing flap position and a reduced reference speed of 1.13 V S (1.13 times the stall speed, English stall , therefore V S ).

Objective of Bombardier Aerospace pilots was on that flight beyond a steady Heading Sideslip shortly SHSS, ( sideslip ) with a stable course to 8 ° extended landing flaps, a WS148-casing and 1.13 V S to perform. The stall protection systems ( stick shaker and stick pusher ) were set with retracted landing flaps and other landing flap configurations (20 °, 30 °, 45 °) so that they should be triggered as soon as there was a WS148 in the aircraft that is neither side-gliding nor a WS148 has nose cone, the stall occurs or this already threatened. With the landing flaps extended by 8 °, the protective systems were set in such a way that the additional lift from the WS-148 fairing was included, which means that the protective systems would only be triggered at a higher angle of attack . The effects of a side-glide flight on the sensors that transmit the data for protection systems have not yet been checked for the new flap configuration. The aerodynamicists informed the pilots that the data collected would be sufficient if either the stall warning was issued to prevent the stick pusher from intervening, or the lateral glide angle reached a value of 15 °, the latter being the criterion for certification.

course

The aircraft took off at 1:31 p.m. from Wichita Mid-Continent Airport on a test flight under visual flight rules , for which no flight plan was submitted to the FAA . This test flight was carried out in order to be able to evaluate the flight characteristics of the aircraft during take-off with the flaps extended by 8 ° and to demonstrate compliance with the US 14 CFR 25: 177 rules. After the start and a trim test, the test engineer read out the test conditions for the SHSS: A calculated 1.13 V S speed of 146 kn (270 km / h ); Flaps extended 8 °; Landing gear retracted, as confirmed by the captain and first officer . At an altitude of 12,500 ft (3810 m ), with the engines idling , the pilot moved the rudder progressively to the right while the first officer read the beta values. After the first officer read a beta value of 12, the flight captain noted: "Buffet starts" (the buffet begins). The chief test pilot later stated that these were incidental vibrations of the airframe from the side glide flight. The stick shaker set in at a beta value of 17. Then the first officer began to read off the alpha values ( angle of attack ) in addition to the beta values . With an alpha value of 11 and a beta value of 19, the master noted: “a little bit of pitch instability” and then “on the stop” (full rudder) while the first officer read a beta value of 21. Then the flight captain reported that the aileron was decreasing and the acoustic stall warning sounded. The aircraft rolled to the right around its longitudinal axis at 13:51:25 , sinking to 11,500 ft (3,500 m), entering a deep stall , and alpha exceeding a record limit of 35 units. The first officer then asked the captain: "want me to release the chute", to which the captain replied vaguely: "stop (at)". The first officer then asked: "at eight", whereupon the captain gave the instruction: "Chute out" and then asked whether the parachute was out, whereupon the first officer said: "yeah" ( yes) answered. As a result, at 13:51:56, at an altitude of 6,800 ft (2070 m) and a speed of 190 kn (350 km / h), the aircraft nose lowered and the aircraft leaned over 60 ° to the right and 60 ° downwards, with the pilots were unable to regain control and eventually crashed at 1:52 p.m. in a flat cultivated field near Byers, Kansas at 1,970 ft (600 m) altitude. The debris caught fire and slid 650–700 ft (200–215 m) further. The three inmates suffered fatal injuries.

Investigations

In the accident, the flight data acquisition system recorder (ADAS) was destroyed; however, a significant amount of magnetic tape remained on the spool of the broken take-up spool. The evaluated data showed that all systems were working properly. A tear in the tape ended the record at an altitude of 5,700 ft (1,740 m); the rest of the magnetic tape could not be found. The F1000 model flight data recorder (FDR) broke into three pieces. The data store was not found until one day later, 715 ft (220 m) away from the point of impact, due to a lack of identification. When evaluating the data, it was found that more than 20 parameters, including altitude and speed, were not recorded, that the flight data recorder data matched that of the flight data acquisition system recorder, and that the flight data recorder recorded an additional eight seconds. From the data it could be seen that shortly before the impact the engines were working at high speed, the pitch decreased from more than 62 ° downwards to 38 ° downwards and an acceleration of more than 4.5 g acted on the aircraft . The A100A voice recorder was found with slight damage.

The investigations finally revealed the following factors that were responsible for the accident:

The failure of the captain to abort the test maneuver according to the flight plan when inserting the stick shaker
The failure of pilots to properly configure the aircraft for anti-spin parachute ejection. They forgot to press the switches that were supposed to close the jaws, so that the anti-spin parachute did not get caught on the aircraft
The inadequate construction of the anti-spin parachute device, which was based on the situation in which the system was automatically triggered at low altitude or high speed and thus enabled it to be operated with the jaws open

Above: normal flight; Below: “Deep Stall” - tailplane in the slipstream

Similar cases

On British Aircraft Corporation Flight 53 , a BAC 1-11 crashed under similar circumstances.
In the aircraft accident involving the Hawker Siddeley Trident G-ARPY , a Hawker Siddeley Trident crashed under similar circumstances.

Web links

Description of CFR 25: 177 rules in English

swell

Aircraft accident data and report C-FRCJ in the Aviation Safety Network (English)

Remarks

↑ This refers to the anti-spin parachute , which is used to divert aircraft from extremely critical flight phases, such as a deep stall or flat spin , which are practically impossible with conventional countermeasures such as pushing the control horn forwards - among other things due to special aerodynamic effects are divertable.

[1] This refers to the anti-spin parachute , which is used to divert aircraft from extremely critical flight phases, such as a deep stall or flat spin , which are practically impossible with conventional countermeasures such as pushing the control horn forwards - among other things due to special aerodynamic effects are divertable.