Ferrographic and spectrometer oil analysis from a failed gas turbine engine

An experimental gas turbine engine was destroyed as a result of the combustion of its titanium components. It was concluded that a severe surge may have caused interference between rotating and stationary compressor that either directly or indirectly ignited the titanium components. Several engine oil samples (before and after the failure) were analyzed with a Ferrograph, a plasma, an atomic absorption, and an emission spectrometer to see if this information would aid in the engine failure diagnosis. The analyses indicated that a lubrication system failure was not a causative factor in the engine failure. Neither an abnormal wear mechanism nor a high level of wear debris was detected in the engine oil sample taken just prior to the test in which the failure occurred. However, low concentrations (0.2 to 0.5 ppm) of titanium were evident in this sample and samples taken earlier. After the failure, higher titanium concentrations ( 2 ppm) were detected in oil samples taken from different engine locations. Ferrographic analysis indicated that most of the titanium was contained in spherical metallic debris after the failure. The oil analyses eliminated a lubrication system bearing or shaft seal failure as the cause of the engine failure

Aeroplane design study STOL airliner (A71). Part 2- detail design features

This report is concerned with a description of the detail design features of the A71 project study. This aircraft is an airliner designed for operation off single 2000 ft long runways. The overall description of the design and its aerodynamic characteristics are contained in Part I of the report (Ref.1). The detail design of the structure and systems is conventional in most respects. The need to provide a long stroke undercarriage for STOL operations incurred a large weight penalty and it is concluded that further work is necessary to establish acceptable requirements for this type of undercarriage. A separate investigation (Ref.3) has shown that the aircraft does not meet its stipulated design objectives due to an inability to cope with engine failure and gusting cross wind conditions. A study to investigate the potential of the cross-coupling of adjacent powerplants to mitigate engine failure control problems suggests that the weight penalty is not justified (Ref.-)

The Effect of Modified Control Limits on the Performance of a Generic Commercial Aircraft Engine

This paper studies the effect of modifying the control limits of an aircraft engine to obtain additional performance. In an emergency situation, the ability to operate an engine above its normal operating limits and thereby gain additional performance may aid in the recovery of a distressed aircraft. However, the modification of an engine s limits is complex due to the risk of an engine failure. This paper focuses on the tradeoff between enhanced performance and risk of either incurring a mechanical engine failure or compromising engine operability. The ultimate goal is to increase the engine performance, without a large increase in risk of an engine failure, in order to increase the probability of recovering the distressed aircraft. The control limit modifications proposed are to extend the rotor speeds, temperatures, and pressures to allow more thrust to be produced by the engine, or to increase the rotor accelerations and allow the engine to follow a fast transient. These modifications do result in increased performance; however this study indicates that these modifications also lead to an increased risk of engine failure

A simulator investigation of engine failure compensation for powered-lift STOL aircraft

A piloted simulator investigation of various engine failure compensation concepts for powered-lift STOL aircraft was carried out at the Ames Research Center. The purpose of this investigation was to determine the influence of engine failure compensation on recovery from an engine failure during the landing approach and on the precision of the STOL landing. The various concepts include: (1) cockpit warning lights to cue the pilot of an engine failure, (2) programmed thrust and roll trim compensation, (3) thrust command and (4) flight-path stabilization. The aircraft simulated was a 150 passenger four-engine, externally blown flap civil STOL transport having a 90 psf wing loading and a .56 thrust to weight ratio. Results of the simulation indicate that the combination of thrust command and flight-path stabilization offered the best engine-out landing performance in turbulence and did so over the entire range of altitudes for which engine failures occurred

Optimized Engine Out Procedures to Extend the Range of Jet Transport Airplanes

The purpose of this study was to develop optimum engine-out procedures for the Boeing 747 and 767 on extended flights that will increase the range of the aircraft in case of engine failure. Theory suggests that an optimum amount of bank angle that will minimize drag resulting from asymmetric thrust in a multiengine airplane experiencing an engine failure, can be determined. By banking the airplane into the operative engines by that optimum bank angle, the range of the airplane can be improved significantly. Wind tunnel tests of both a Boeing 747 and a 767 model were performed to determine experimentally the increase in range that can be achieved by the zero slip position. By comparing the drag force coefficient obtained at the sideslip position that occurs due to an engine failure with the drag force coefficient obtained at the wings level condition for each airplane, the amount that their specific range will increase was determined

The Effect of Expertise during Simulated Flight Emergencies on the Autonomic Response and Operative Performance in Military Pilots.

Heart rate variability (HRV) and performance response during emergency flight maneuvers were analyzed. Two expert pilots (ages 35 and 33) and two rookie pilots (ages 25) from the Portuguese Air Force participated in this case–control report study. Participants had to complete the following emergency protocols in a flight simulator: (1) take-off engine failure, (2) flight engine failure close to the base, (3) flight engine failure far away from the base, and (4) alternator failure. The HRV was collected during all these maneuvers, as well as the performance data (the time it took to go through the emergency protocol and the subjective information from the flight simulator operator). Results regarding autonomic modulation showed a higher sympathetic response during the emergency maneuvers when compared to baseline. In some cases, there was also a higher sympathetic response during the emergency maneuvers when compared with the take-off protocol. Regarding performance data, the expert pilots accomplished the missions in less time than the rookie pilots. Autonomic modulation measured from HRV through portable devices can easily relay important information. This information is relevant since characterizing these maneuvers can provide helpful information to design training strategies to improve those psychophysiological responses

Is “Green Dot” Always the Optimum Engines-Out Glide Speed on the Airbus A320 Aircraft?

The dual-engine failure checklist of the Airbus A320 states that the optimum airspeed at which the aircraft can be flown is the “green dot” speed when an engine restart is considered impossible. This is because the “green dot” speed maximizes the power-off glide range in wings-level flight. However, it is not known whether the “green dot” speed would still be the optimum airspeed if the power-off landing maneuver primarily consists of sharp turns. The objective of this study is to find out the optimum power-off glide speed for the A320 if the emergency landing maneuver primarily requires sharp turns rather than wings-level flight. For this purpose, the study analyzes a total-loss-of-power scenario, in which an A320 undergoes dual-engine failure due to bird strike during the initial climb-out, and attempts a turn-back maneuver to the departure runway. The results show that the optimum power-off glide speed would be the lowest selectable airspeed because it requires the lowest altitude loss to reach the departure runway, enables the most favorable bank angle history, and requires the shortest runway length for landing roll. Therefore, the statement that the “green dot” speed is the optimum power-off glide speed may be a misleading item in the dual-engine failure checklist of the A320 in emergency situations. The findings can be used to revise and improve the existing dual-engine failure checklist of the Airbus A320, which transports over 71.5 million annual passengers on U.S. air carriers (Research and Innovative Technology Administration [RITA], 2014). This study is also the first of its type to analyze the power-off glide performance of a commercial jet

Space engine safety system

A rocket engine safety system was designed to initiate control procedures to minimize damage to the engine or vehicle or test stand in the event of an engine failure. The features and the implementation issues associated with rocket engine safety systems are discussed, as well as the specific concerns of safety systems applied to a space-based engine and long duration space missions. Examples of safety system features and architectures are given, based on recent safety monitoring investigations conducted for the Space Shuttle Main Engine and for future liquid rocket engines. Also, the general design and implementation process for rocket engine safety systems is presented

Preliminary design-lift/cruise fan research and technology airplane flight control system

This report presents the preliminary design of a stability augmentation system for a NASA V/STOL research and technology airplane. This stability augmentation system is postulated as the simplest system that meets handling qualities levels for research and technology missions flown by NASA test pilots. The airplane studied in this report is a T-39 fitted with tilting lift/cruise fan nacelles and a nose fan. The propulsion system features a shaft interconnecting the three variable pitch fans and three power plants. The mathematical modeling is based on pre-wind tunnel test estimated data. The selected stability augmentation system uses variable gains scheduled with airspeed. Failure analysis of the system illustrates the benign effect of engine failure. Airplane rate sensor failure must be solved with redundancy