Downloads from this page:

Video YouTube

Several formal references.

1. Three page intro paper.
2. Control and performance during asymmetrical powered flight.
3. Airplane Control and Accident Investigation after Engine Failure
4. Imperfections in Regulations
5. EASS: Staying alive with a dead engine
6. The effect of Bank Angle and Weight on VMCA.

7. FAA Multi-engine safety review.

8. Review of FAA-H-8083-3A Chapter 12, Transition to Multi-engine Airplanes
8a. Flying Light Twins Safely
9.
Review of CAAP 5.23-2(0).
10. PA-44 docs.
11. B737-200

 

Downloads in Dutch language 

Press Release


Publications by AvioConsult for download

Introduction

All across the globe, accidents with both small and big multi-engine airplanes continue to happen quite frequently following the failure of an engine during takeoff, go-around, approach for landing and during engine-out training, despite the fact that all airplane types are thoroughly flight-tested and operational limitations are published in the Airplane Flight Manuals.  Since 1996, more than 395 of such accidents were reported on the Internet alone, causing 3,600 casualties. 
Download the list of engine failure related accidents here.

The cause of these accidents is that the
minimum control speed in the air (VMC or better VMCA) is considered to be a safe minimum speed for maintaining control when an engine is inoperative.
But it is not; the vertical tail with rudder is sized for maintaining straight flight only at VMCA. Airplane design engineers apply a bank angle of a few degrees (max. 5, i.a.w. FAR 23.149, 25.149 and equivalent) away from the inoperative engine for the sideslip to be minimal at VMCA.  When using a small bank angle, the vertical tail can be made smaller, hence cheaper and less heavy, the sideslip / drag can be reduced to a minimum and hence, the remaining climb performance increased to maximum. The VMCA is lower, safer than with the wings level or at other bank angles. 
The VMCA / VMC that is published in Flight Manuals is determined during flight-testing while also maintaining both this small bank angle and straight flight (i.a.w. ref's 2 - 4 and 10 and 11 below).  Any other bank angle (i.e. turning) increases both the actual VMCA and the drag.

Consequently, the vertical tail of a multi-engine airplane is usually not designed large enough for maintaining control during turns at airspeeds as low as VMCA while an engine is inoperative and the power setting on the opposite engine is maximum.  During turns at asymmetrical power, performance will be lost due to the increase of sideslip or even fin stall, and control might be lost.  Loss of Control In-flight cannot be prevented at low airspeeds when a high asymmetrical thrust setting is maintained.  It is this knowledge that might be lost during the past 50 years.

In order to bridge the obviously existing gap in knowledge of airplane control after a propulsion system malfunction between airplane design & flight-test and airplane operations & accident investigation, a number of papers are made available for download that explain the real value of the seven types of VMC and the important conditions that are required for the Flight-Manual-published VMC(A) to be valid, in order to prevent accidents after engine failure in the future and to improve the analysis of accidents after engine failure.

A correct VMCA definition for pilots would be:

VMCA is the minimum speed for maintaining straight flight when an engine fails or is inoperative and the corresponding opposite engine is set to provide maximum thrust, provided a bank angle is being maintained of 3 5 degrees (exact number to be provided by the manufacturer) away from the inoperative engine.

The papers presented below are written using airplane design books as used by aeronautical universities, formal FAA and EASA Flight Test Guides (ref's 2 - 4) and the asymmetrical power course used by formal Test Pilot Schools for Experimental Test Pilots and Flight Test Engineers (Ref's 10 and 11 below).  

What is VMCA or VMC?

A 42 min. video lecture, in which the real value of the minimum control speed airborne (VMCA) is explained as taught at all formal Test Pilot Schools and most aeronautical universities. Click here to start the video from the beginning, or follow direct links to the subjects:
Control after Engine failure
Limits due to tail design
Effect of Bank angle and weight
Critical Engine
Flight testing VMCA
Deficient VMCA Definition
Improved VMCA Definition
Takeoff speed
Accident EMB-120ER analyzed
Do's and Don'ts when OEI
A pdf file with slides and script used in this video can be downloaded here

Click here to open a separate window with explanation on VMCA or download and read the formal FAA and EASA Flight Test Guides and FAR and CS 23.149 (and 25.149), the VMCA paragraphs of which are listed in and downloadable from the list of formal References below. 

References:

The following formal documents were used for writing the papers available on this website.  
A few comment boxes are included on some of the pages for clarification:

1.   On-line One Engine Inoperative Trainer, University of North Dakota, click here.
2.   FAA Flight Test Guide, AC23-8C, pages on VMCA testing, click here.
3.   EASA Certification Specification 23, Flight Test Guide, VMCA testing, click here.
4.   FAA Flight Test Guide, AC25-7C, pages on VMCA testing, click here.
5.   FAA Federal Aviation Regulations Part 23.149 on VMCA, click here.
6.   EASA Certification Specification 23.149 on VMCA, click here.
7.   FAA Federal Aviation Regulations Part 23, 25, etc., click here.
8.   EASA Certification Specification 23, click here. All CS's, click here.
9.   Airplane Design, Dr. Jan Roskam, University of Kansas/DARcorporation, click here.
10. US Naval Test Pilot School, Flight Test Manual Chapter 6 on Asym Power, pdf file, click here.
11. USAF Test Pilot School, Chapter 11 Engine-Out Theory, 1.8 MB pdf file, click here.

In addition, all graduate Test Pilots and Flight Test Engineers of the major Test Pilot Schools in the USA, UK and FR will be able to confirm that the papers presented on this website are indeed correct.

Papers with background theory 

1.  Controlling Airplanes after Engine Failure - Tail Design Imposed Limitations
In only 3 pages, the most important operating limitations for flight with an inoperative engine, that are consequences of the methods used to design the vertical tail of a multi-engine airplane and the experimental flight test to determine the minimum control speed in the air (VMCA), are briefly explained.  First published 2008, last updated May 2016.

Download this paper  (for free)
  Also available in the Dutch language here.

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2.  Control and Performance during Asymmetrical Powered Flight  
For multi-engine rated pilots.    

Detailed paper in accordance with the JAA (and FAA) Learning Objectives, FAR's and EASA CS's for Multi-engine Rated Pilots, CPL & ATPL.  Based on Airplane Design Methods as taught by Aeronautical Universities and on Flight Test Techniques as taught by Experimental Test Pilot Schools.
28 pages, 26 figures, 2 MB pdf. 
First published January 2012, updated May 2016.

Download this paper (for free)
 

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3.  Airplane Control and Analysis of Accidents after Engine Failure
For flight instructors and accident investigators

For accident investigators, engineering & test pilots, manual and book writers, flight-instructors and pilots who want to know it all.  Published May 2012.  71 pages.

Many accident investigators, engineering/ test pilots and Flight Manual writers explain and use the VMCA of an airplane not in the same way as airplane design engineers, experimental test pilots and flight test engineers do. 
To the opinion of AvioConsult, the limitations and conditions used during designing and flight-testing a multi-engine airplane are not appropriately passed on to (airline) pilots in manuals and during flight training.  Many pilots,  investigators and manual writers just use text out of Regulations (Part 23, 25) that are intended for designing and for the certification of airplanes, but definitely not for their operational use.  

This paper, written by a Test Pilot School graduate, explains airplane control while the thrust is asymmetrical and also engine-out climb performance and the many factors that have influence on control and performance.  Seven types of VMC are discussed, as are the flight-test methods to determine these minimum control speeds (VMC's).   The conditional safety of VMCA and of the derived V1 and V2 are explained, because inadequate accident reports show this is required.  A few incorrect definitions of VMCA in Flight and Operating Manuals are discussed as are inappropriate engine emergency procedures. Training and demonstration of VMCA in-flight, including cautions, are included as well.

FDR data plot Included in this paper are analyses of 6 engine failure accidents that actually happened. Three of these fatal accidents (EMB-120ER, Saab SF-340B, Jetsream 4100) are analysed step by step using Flight Data Recorder (FDR) data as illustrated in the adjacent figure.  

After reading this paper, airplane accident investigators will be able to improve the analysis of airplane accidents following a propulsion system malfunction and write much better and appropriate conclusions and recommendations in accident investigation reports. These reports will become much more valuable for preventing propulsion system malfunction related accidents and incidents in the future. 

Pilots will understand the conditions for which VMCA, VR and V2 are valid much better, will improve airplane control after engine failure, know how to achieve best climb performance and will never crash anymore due to the loss of control while an engine is inoperative. 
M
anual and procedure writers will understand VMC's much better and use the gained knowledge to improve definitions of VMC's and engine failure procedures in Flight and Operating Manuals.  
All readers will understand engine-out performance and the real value of the VMC's that are listed in all Flight Manuals of multi-engine airplanes, as well as the conditions for which VMC's are valid. 

Reading and understanding this paper will prevent the loss of control 
and performance after propulsion system malfunctions 
in the future.

Download the title page, table of contents and the introduction of this paper for free here.
Click the BUY NOW button for buying a single copy of the full 71-page paper for 4.99 (~US$ 5.30).  
Last updated: 2016-11-17.

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R
equired Data for Investigating Engine Failure Related Accidents

Manual Writers and Accident Investigators might find this list (free) of use for verifying whether Flight and Ops Manual data on engine-out flight are complete, and for making sure all data is available for Engine Failure Related Accident Investigations and Analyses.

To assist in reading FDR data plots more accurately, print either of these free grid sheets on a transparent sheet using a laser printer:

 

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4. Imperfections and Deficiencies in FAA and EASA Regulations 
A paper that resulted from the research for the papers presented above. It presents and explains imperfections found in aviation regulations that might lead to accidents after engine failure and includes ready-to-copy suggestions for improvement

5. Staying Alive with a Dead Engine  
A paper presented to the European Aviation Safety Seminar of the Flight Safety Foundation in Athens, Greece in March 2006.  The paper addresses the 4 errors that can be found in the definition of VMCA in the Flight Manual of almost all airplanes and explains that there is an important condition for both the minimum control speed VMCA and the takeoff safety speed V2 to be valid. 

This paper is also available from the Flight Safety Foundation on the CD-ROM that contains all EASS 2006 papers. 

6. The Effect of Bank Angle and Weight on VMCA 
In the papers  presented above (1, 2 and 3), a few graphs showing the effect of bank angle and weight on VMCA and on takeoff safety speed V2 are included.  These graphs were calculated using a prediction method that is also used by experimental test pilots and flight test engineers before conducting the flight-tests to determine VMCA in order to learn about limitations, etc. that might be encountered during the test flights.  This paper presents the prediction method and includes a few data figures.  This method can be used for all multi-engine airplanes, provided the required stability derivative data are available. 

Review of Flight  and Training Manuals

7. FAA Multi-Engine Safety Review.
The FAA Course Notes Multi-Engine Safety Review that is presented on the FAASafety website, was reviewed by AvioConsult using the knowledge of experimental flight testing.  The Course notes - as of Aug. 2012 - do not agree with Flight Test Techniques used to determine VMCA as taught at Test Pilot Schools (ref's 10 and 11 above) and as published in FAA Flight Test Guides in Advisory Circulars (references 2 and 4 above).  This paper presents many suggestions for improvement which are definitely required to improve the Notes and therewith flight safety. 

Download this paper with recommendations for improvement   |  Top
8. FAA-H-8083-3A/B, Chapter 12, Transition to Multi-engine Airplanes.
Airplane Flying Handbook FAA-H-8083-3A/B, Chapter 12 "is devoted to the factors associated with the operation of small multi-engine airplanes".  This Chapter was also reviewed by AvioConsult using the knowledge of experimental flight testing.  This Chapter - as of Aug. 2012 - regrettably does neither agree with the design methods for sizing the vertical tail of multi-engine airplanes, as taught at aeronautical universities, nor with the Flight Test Techniques used to determine the engine-inoperative flying qualities, including VMCA, as taught at Test Pilot Schools (ref's 10 and 11 above) and not even as published in FAA Flight Test Guides in Advisory Circulars (ref's 2 and 4 above).  Besides a review, this paper presents many suggestions for improvement which are definitely required to improve the transition to multi-engine airplanes and prevent accidents after engine failure.  

Download this paper
   |  Top
8a. Flying Light Twins Safely. FAA-P-8740-66.
This publication provides the aviation community with safety information, but must be improved to really increase safety and reduce the rate of engine failure related accidents. The recommended improvements are included in text boxes.
Download this paper with recommendations for improvement   |  Top
9. CASA CAAP 5.23-2(0), Multi-engine Aeroplane Operations and Training.
This document was referenced in the accident report of a PA-31P-350 in Bankstown, 15 June 2010 and reviewed.  Although all ingredients of flight with an inoperative engine are included, somehow it became clear that VMCA & VMC and the conditions that apply with these minimum control speeds were not clear to the authors of the accident report, and hence will not be understood by pilots, resulting again in accidents.  Improvement is definitely required, therefore this paper also presents suggestions for improvement. 
Download this paper  |  Top
10. PA-44-180 Seminole documents
A limited review of PA-44-180 Seminole documents, as used by flight schools (and by other PA-44 owners).  It should also be useful to operators of other multi-engine airplane types.
Download this paper  |  Top
11. Boeing 737-200/300/400 Flight Crew Training Manual
A limited analysis of the Engine Failure Takeoff Procedures in the Boeing 737-200/300/400 Flight Crew Training Manual.  
This analysis was written following a review of the accident investigation report of the accident with an Algerian 737 on 6 March 2003.

Download this analysis  |  Top

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