john_tullamarine
5th Aug 2002, 22:16
As the subject of Vmca regularly pops up in this, and other, forums, the following recent advice from a major regulatory body may be useful for ME instructors, and ME pilots generally, to review.
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THE Vmc DEMO
Both the private and commercial practical test standards for a multiengine class rating require a Vmc demonstration. Previous PTS Books (FAA-S-8081-12A and FAA-S-8081-14) contained a "NOTE" reference this task which advised that airplanes with normally aspirated engines will lose power as altitude increases, and the loss of power may result in a Vmc lower than stall speed at higher altitudes. Also, some airplanes have such an effective rudder that even at sea level Vmc is lower than stall speed. The note went on to say that in these airplanes a demonstration of loss of directional control may be safely conducted by limiting rudder travel to simulate maximum available rudder. The information in this note was intended to be informative rather than directive.
The information regarding limiting rudder travel to simulate maximum available rudder does not appear in the new practical test standards which become effective August 1, 2002, and as an answer to questions we have received regarding this issue, we would like to emphasize that the omission is intentional. It is FAA policy that "blocking the rudder" during the Vmc demonstration task on a practical test is not an acceptable method of demonstrating or evaluating this maneuver. During training however, single engine procedures should be practiced to prepare for an actual emergency situation, not just a practical test demonstration. In the training situation "blocking the rudder" has been, and will continue to be, an acceptable and productive method of teaching single engine procedures. As recovery ability is gained with practice, the speed at which the maneuver is started may be lowered in small increments until the feel of the aircraft in emergency conditions is well known. Practice should be continued until an instinctive corrective reaction is developed, and the corrective procedure is automatic. In a training situation, restricting rudder travel in effect sets up an artificial situation which is very useful in the interest of safety. By the time a student's training is complete, and he/she is ready for a practical test, the student should be well versed in the effects of density altitude on Vmc, the relationship of Vmc to stall speed, reasons for loss of directional control, indications of loss of directional control, loss of directional control recovery procedure, and the critical importance of never allowing the airplane to enter a stall with one engine inoperative. This is what the
applicant will demonstrate on the practical test, not just the ability to mechanically approach a loss of control situation and recover.
It must be remembered that the practical test standards are designed to be "testing documents" rather than "teaching documents". The practical test standard books contain the standards to which a particular maneuver/procedure must be accomplished. Information on teaching and performing specific maneuvers is contained in the Airplane Flying Handbook (FAA-H-8083-3) and the Pilot's Operating Handbook for the specific make and model airplane. The practical test standards do not require an actual loss of control on a Vmc demonstration. This has not changed. The practical test standards require that an applicant recognize any indications of loss of directional control, or stall warning, or stall buffet, and recovers promptly and correctly when either is encountered.
Artificially limiting rudder travel defeats this purpose. Pilot's Operating Handbooks for popular light twin engine training airplanes such as Piper PA-34, PA-31, PA-44, Cessna 402, BE-76 and BE-58 make no mention of limiting rudder travel during Vmc demonstrations on FAA practical tests. Almost invariably the POH's for these and other aircraft recommend that recovery be initiated at Vmc, stall warning, or stall buffet, as in the Practical Test Standards.
unquote
quote
THE Vmc DEMO
Both the private and commercial practical test standards for a multiengine class rating require a Vmc demonstration. Previous PTS Books (FAA-S-8081-12A and FAA-S-8081-14) contained a "NOTE" reference this task which advised that airplanes with normally aspirated engines will lose power as altitude increases, and the loss of power may result in a Vmc lower than stall speed at higher altitudes. Also, some airplanes have such an effective rudder that even at sea level Vmc is lower than stall speed. The note went on to say that in these airplanes a demonstration of loss of directional control may be safely conducted by limiting rudder travel to simulate maximum available rudder. The information in this note was intended to be informative rather than directive.
The information regarding limiting rudder travel to simulate maximum available rudder does not appear in the new practical test standards which become effective August 1, 2002, and as an answer to questions we have received regarding this issue, we would like to emphasize that the omission is intentional. It is FAA policy that "blocking the rudder" during the Vmc demonstration task on a practical test is not an acceptable method of demonstrating or evaluating this maneuver. During training however, single engine procedures should be practiced to prepare for an actual emergency situation, not just a practical test demonstration. In the training situation "blocking the rudder" has been, and will continue to be, an acceptable and productive method of teaching single engine procedures. As recovery ability is gained with practice, the speed at which the maneuver is started may be lowered in small increments until the feel of the aircraft in emergency conditions is well known. Practice should be continued until an instinctive corrective reaction is developed, and the corrective procedure is automatic. In a training situation, restricting rudder travel in effect sets up an artificial situation which is very useful in the interest of safety. By the time a student's training is complete, and he/she is ready for a practical test, the student should be well versed in the effects of density altitude on Vmc, the relationship of Vmc to stall speed, reasons for loss of directional control, indications of loss of directional control, loss of directional control recovery procedure, and the critical importance of never allowing the airplane to enter a stall with one engine inoperative. This is what the
applicant will demonstrate on the practical test, not just the ability to mechanically approach a loss of control situation and recover.
It must be remembered that the practical test standards are designed to be "testing documents" rather than "teaching documents". The practical test standard books contain the standards to which a particular maneuver/procedure must be accomplished. Information on teaching and performing specific maneuvers is contained in the Airplane Flying Handbook (FAA-H-8083-3) and the Pilot's Operating Handbook for the specific make and model airplane. The practical test standards do not require an actual loss of control on a Vmc demonstration. This has not changed. The practical test standards require that an applicant recognize any indications of loss of directional control, or stall warning, or stall buffet, and recovers promptly and correctly when either is encountered.
Artificially limiting rudder travel defeats this purpose. Pilot's Operating Handbooks for popular light twin engine training airplanes such as Piper PA-34, PA-31, PA-44, Cessna 402, BE-76 and BE-58 make no mention of limiting rudder travel during Vmc demonstrations on FAA practical tests. Almost invariably the POH's for these and other aircraft recommend that recovery be initiated at Vmc, stall warning, or stall buffet, as in the Practical Test Standards.
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