Lauda Air Flight - Wikipedia
This is the talk page for discussing improvements to the Lauda Air Flight article. Please sign and date your posts by typing four tildes (~~~~). . I asked to fly the simulator myself with it programmed the way they thought the aeroplane . Lauda Air Flight was a regularly scheduled international passenger flight between Date, 26 May . Lauda asked Boeing to fly the scenario in a simulator that used different data as compared to the one that Lauda had performed. I was a Boeing ER, built in and delivered to Lauda Air in . Lauda decided to recreate my last flight in a simulator to figure out.
Lauda attempted the flight in the simulator 15 times, and in every instance he was unable to recover. He asked Boeing to issue a statement, but the legal department said it could not be issued because it would take three months to adjust the wording. Lauda asked for a press conference the following day, and told Boeing that if it was possible to recover, he would be willing to fly on a with two pilots and have the thrust reverser deploy in air.
Boeing told Lauda that it was not possible, so he asked Boeing to issue a statement saying that it would not be survivable, and Boeing issued it.
Lauda Air Flight - Simple English Wikipedia, the free encyclopedia
Lauda then added, "this was the first time in eight months that it had been made clear that the manufacturer [Boeing] was at fault and not the operator of the aeroplane [or Pratt and Whitney]. Boeing had insisted that a deployment was not possible in flight. In Boeing established a test where the aircraft was slowed to knots, and the test pilots then used the thrust reverser.
The control of the aircraft had not been jeopardized. Although damaged, it was successfully read out, and a transcript extract of its contents is included in this report as Appendix A. The average elevation of the wreckage area was estimated to be metres. Most of the wreckage was found in a one square kilometer area, but some lighter weight components were found up to 2, metres from the initial impact point.
Thrust reverser actuators from the left engine both sleeves were found in the fully deployed position. A diagram of the wreckage spread is included in this report as Appendix B. No fire fighting activities took place due to the remote location and general inaccessibility of the accident site. The limited number and the degree of damage to the components precluded a determination of functional condition.
Approximately 9 months after the accident, the DCV was returned to Department of Aviation by persons not associated with the accident investigation. The DCV was exchanged for a reward. This is the normal position for the valve without hydraulic pressure applied.
Further examination of the spring that holds the second stage spool in position indicated that it was intact. The examination of the DCV also revealed that 3 of 4 screws used to secure the solenoid operated pilot valve body to the DCV were loose.
Soil was found inside internal passages of the valve.
Lauda Air Flight 004
A metal plug, identified as a case relief valve plug used elsewhere in the engine accessory section, was found installed "finger tight" in the DCV "retract" port.
All solenoid operated pilot valve first stage spool internal passages were unobstructed.
There was no evidence that indicated preimpact failure of the valve, however the condition of the valve indicated that the valve was partially disassembled and reassembled by persons not associated with the accident investigation prior to examination by the investigation team. Additional system tests were performed using production components in an attempt to simulate potential failure modes.
In one hypothetical condition, the introduction of a damaged piece of O-ring seal into a hydraulic orifice resulted in an uncommanded opening of the directional control valve DCV. For further information on these tests, see paragraph 2. Testing of the electrical function indicated possible areas where an electrical hot short occurring simultaneously with an auto-restow action could result 11 in uncommanded opening of the DCV for up to one second.
A full hydraulic set-up was used to verify normal operation of the thrust reverser system and to determine if uncommanded deployment could occur under various hypothetical failure conditions. Hypothetical failure conditions involved the directional control valve DCV seal damage, thrust reverser actuator piston head seal leakage and a return line blockage during hydraulic isolation valve HIV cycling.
Also, a vibration test simulating the vibration environment of the DCV during it's life was performed. In another hypothetical failure condition, the effects of piston seal leakage through a thrust reverser actuator was examined with the HIV open. Several test configurations were examined with the piston head O-ring and cap strip missing from the actuator s. Only one side one of two sleeves of the thrust reverser cowl deployed when an actuator was tested with the piston head seal missing and the bronze plating separated from the piston head.
Under this condition, with the HIV open, internal leakage across the piston was sufficient to deploy the 3 actuators associated with the deployed sleeve depending on the location of the actuator piston head in the cylinders. If in the stow position and the piston heads were firmly bottomed against the inner cylinder head end prior to commanding thrust reverser stow, the thrust reverser actuators would not deploy.
When the head end of the two actuators were slightly unseated, fluid could pass from the rod end to the head end of the locking actuator causing unlock and extension of 3 actuators one sleeve.
Examination of the thrust reverser actuators from the left engine of the accident airplane was not conclusive, because only one piston head and it's associated seal was recovered from the accident site.
The cap strip from this actuator piston head had considerable wear and was extruded. A DCV was mounted on a vibration table and subjected to resonant searches, resonant dwells, random vibration and sweeps through engine speed 12 ranges in three axes while under constant and pulsing pressure in the hydraulic lines.
Pressure transducers and flow meters on the outflow of the valve indicated that the valve did not open unexpectedly or leak during the test under excessive vibration.Lauda Air Crash Site - Thailand
The thrust reversers are approved for ground operation only. A general systems description is included in this report as appendix C.
Oh no, there's been an error
The FAA issued information on the accident to appropriate operators and authorities on September 11, by letter format. It is included in this report as appendix E. ADJuly 3, - Requires tests, inspections and functional checks of the thrust reverser systems on all B airplanes powered by Pratt and Whitney PW series engines. This superseded AD This superseded TAD 1. AD 9October 11, - Requires modification and allowed re-activation of thrust reverser systems on all B airplanes powered by Pratt and Whitney PW series engines.
This superseded TAD Since this information was critical to the investigation, a search was conducted to identify non-volatile memory in various computerized components as an alternate source of data.
Lauda Air Flight
The data developed proved helpful in validating conditions prior to and during the accident, but did not provide the time correlation normally available with the DFDR. Readouts from such sources are accomplished by manufacturer's personnel in their own laboratories, as these items were not originally designed to support airplane accident investigation activities.
There was no evidence that medical factors or fatigue affected the flight crew's performance. The airplane was certificated, equipped and maintained according to regulations and approved procedures. Flight documents indicate that the gross weight and c. With the exception of some recurring maintenance PIMU messages pertaining to the thrust reverse system which did not preclude dispatching the airplane's sic. The weather in the area was fair at the time of the accident. Although there were no reported hazardous weather phenomena, isolated lightning was possible.
There are few visible landmarks and population centers on the ground along the route of flight and it is possible that the horizon was not distinguishable. Recovery from any unusual flight attitude could have been affected by the lack of outside visual references.
The pilot-in-command stated "that keeps coming on. This indication appears when a fault has been detected in the thrust reverser system. Boeing did not want to say anything. Boeing initially refused, but Lauda insisted. Lauda attempted the flight in the simulator 15 times, and in every instance he was unable to recover.
- Lauda Air Crash 1991: still too many open questions
He asked Boeing to issue a statement, but the legal department said it could not be issued because it would take three months to adjust the wording. Lauda asked for a press conference the following day, and told Boeing that if it was possible to recover, he would be willing to fly on a with two pilots and have the thrust reverser deploy in air.
Boeing told Lauda that it was not possible, so he asked Boeing to issue a statement saying that it would not be survivable, and Boeing issued the statement. Lauda said, "this was the first time in eight months that it had been made clear that the manufacturer was at fault and not the operator of the aeroplane.
Boeing had insisted that a deployment was not possible in flight. In Boeing established a test where the aircraft was slowed to knots, and the test pilots then used the thrust reverser. The control of the aircraft had not been jeopardized. The FAA accepted the results of the test. Chiles, author of Inviting Disaster, said, "the point here is not that a thorough test would have told the pilots Thomas J.