1 757 Pilot Induced Oscillations (PIO) Capt. Leon Robert Chief Project Pilot, Boeing 757 Boeing Commercial Airplanes May 2004 The Boeing Company W100.2 PIO • Continue to get infrequent reports of oscillatory events in the roll axis – Usually on landing (“high gain” pilot task) – Usually in light crosswinds • Review Some Actions Already Taken • Preview More Actions to Come Why are we talking about this? The Boeing Company W100.3 Agenda • What is a Pilot Induced Oscillation (PIO) • What causes a PIO • What we have done already • What we will be doing The Boeing Company W100.4 What is a Pilot Induced Oscillation? • National Research Council Definition: – An inadvertent, sustained aircraft oscillation resulting from a closed-loop interaction between the aircraft dynamics and the pilot’s flight control inputs in which the aircraft response becomes substantially out-of-phase with the pilot input. The Boeing Company W100.5 PIO – A Pilot’s Comments • Pilot must be in the loop – trying to control the airplane – Open-loop control wiggling is not a PIO • Pilot must be out-of-phase with the airplane response – Typically reported as “airplane going the wrong way” or that something in the control system had broken • Event is usually precipitated by a “Trigger” event – External Disturbance – Inadvertent large pilot input – Unanticipated airplane response to an input The Boeing Company W100.6 Actions: • Immediately stop control wheel input • Go-around, if safe landing cannot be made The Boeing Company W100.7 What We Have Done to Date • 09/28/00 Fleet Team Digest Article • 07/05/02 Operations Manual Bulletin • 08/02/02 Flight Operations Technical Bulletin • 11/05/02 Non-Normal Maneuver added to QRH • 11/09/02 Fleet Team Conference • 11/29/02 Flight Operations Symposium • 05/10/04 Flight Operations Symposium Flight Crew Awareness The Boeing Company W100.8 What We Have Done to Date • Vortex Generators on Flaps – Service Bulletin on existing -200 – Production on -300 • Serve to smooth the rapid separation of airflow on the flaps at small spoiler deflections • Makes the roll response more linear, eliminating an “unanticipated response” PIO trigger associated with some crosswind landing conditions Airplane Changes The Boeing Company W100.9 Upcoming Actions • Wheel Damper Installation – Designed to increase the pilot force required to make very large, very rapid wheel inputs – Provides a tactile cue to the pilot that inputs are becoming unnecessarily large and/or fast – Consistent with the Boeing cueing philosophy – Designed to not interfere with “normal” flying Wheel Damper The Boeing Company W100.10 Upcoming Changes • Revised Wheel Force Rigging Procedure – Boeing airplanes use artificial force-feel systems to generate wheel forces – Wheel feel systems include a center “detent” force – Helps hold the wheel in neutral position during unattended operation – Provides a tactile cue to identify neutral wheel Wheel Detent Force The Boeing Company W100.11 Wheel Force Rigging • Some airplanes have higher detent forces than others • Excessive detent forces are potential PIO triggers – Contributes to imprecision in rapid wheel inputs – Potentially generating unanticipated airplane response • Revised rigging procedure will provide adequate wheel centering and minimize the adverse trigger effects – Wheel centering on some airplanes may not be as “crisp” as previously The Boeing Company W100.12 Summary • PIO’s are caused by an adverse interaction between the pilot and the airplane dynamics – Transport airplane dynamics are slow enough that pilots can get out-of-phase – The cycle can be broken by freezing the control inputs – Published Info: Fleet Team Digest, Technical Bulletin, OMB, SB, symposiums • PIO’s are often precipated by “trigger” events – Boeing has been aggressively eliminating potential triggers – Vortilon installation – Wheel damper installation – Revised rigging procedures作者: 979199501 时间: 2011-4-12 14:34:06 标题: 回复 1# 民航 的帖子