AI disconnect for Spin training?

[COOPERVANE]

As a CFI, I routinely demonstrate spin recoveries in the A/C prior to a private student going to his/her checkride. Recently, there was some discussion among CFI's about disconnecting the vacuum system or AI during spin training to prevent damage.
I received my spin training from an 18 year veteran Cessna test pilot. She never mentioned this and I cannot find any info on it. Any thoughts?

 

[jaybird]

How could you possibly disconnect the AI if it's vacume driven by an engine driven vacume pump? Unless you have an electrical one?

 

[COOPERVANE]

I have no clue, I suppose you could disconnect the vacuum somehow but I have NEVER heard of this.

 

[ILLINI]

Hey guys I might be wrong, but I thought the FAA prohibited instructors to intentionally enter spins with students unless it is done during the CFI training for the required spin endorsement. I was under the impression that the only spin training that could be given to students (other than the CFI candidate) was ground instruction.

Was this only a 141 rule or am I just imagining things again?

 

[CornJulio]

Hey guys I might be wrong, but I thought the FAA prohibited instructors to intentionally enter spins with students unless it is done during the CFI training for the required spin endorsement.

Nope; not prohibited at all, unless it was something specific to your 141 school you mentioned, or the airplane manual prohibits it.

You may be thinking of 91.307, which requires parachutes be worn by each occupant, other than required crew, during maneuvers that exceed 60 degrees of bank or 30 degrees of pitch. However, it goes on to specifically exclude "Spins and other flight maneuvers required by the regulations for any certificate or rating when given by...A certificated flight instructor."

Spins are required for "any certificate" (the instructor certificate, specifically), and are therefore exempt from the parachute requirement.

=Julio

 

[newmei]

The FAA put out an Advisory circular saying that CFIs could give spin training even though it is not required for any certificate but the CFI.

A private pilot going up with a passenger would be something entirely different and illegal. (unless you had a a/c with parachutes)

 

[newmei]

In addition, the Decathlon at the flt school had disconnected vacuum supply to the Attitude indicator to prevent tumbling then was legally marked inop. Also on some gyros (like the old seagulls black and white) there is a option to cage the gyro or lock it.

 

[flydog]

Aerobatic manuevers can destroy a gyro if they are severe enough but I dont think a one turn spin during CFI instruction is severe enough. Dedicated aerobatic airplane with gyro instruments have a provision for caging them while flying acro to prevent them from tumbling. As was already stated you cant disconnect a vaccum instrument unless you pull the air hose off it but even if you did it would still tumble.

Bottom line is for CFI spin training its not necessary to cage the gyros as the upset is not that severe.

 

[flydog]

Also a spin is an aerobatic manuever as it easily exceeds the pitch and bank limits of Part 91. You would be exempt from wearing a parachute if you were conducting spin training for a CFI endorsement. The parachute requirement by the way is for passengers only. A PIC flying solo or with passengers would not be required to wear one under any circumstances although his/her passengers would be.

 

[Rvrrat]

AI operating limits

"Safe operating limits of typical air-driven instruments are 60 degrees of pitch and 100 degrees of bank. An electrically driven, self contained AI permits 360 degree rolls & loops without tumbling." excerpt from Modern Airmanship.
I'm of the understanding from my own instructor that recent air-driven AIs are capable of 90 degrees of pitch & 120 degrees of bank though I have not read a tech manual yet to confirm that.

 

[Cornelius]

Another subject, caging gyros while taxiing or airborne isn't good for the instrument as well.

If it is a flight school/rental aircraft and you are performing spins, don't worry about damaging the gyros because usually they are all shot to sh!t anyways.

Peace

 

[avbug]

Flydog,

Any time the flight requires a parachute, the PIC must wear it. You misread the regulation detailed in 14 CFR 91.307(c). Any time an aircraft is carrying someone other than a required crewmember, all occupants must wear parachutes if bank exceeds 60 degrees or pitch 30 degrees. The PIC is not exempt.

Often this is misinterpreted as meaning that all occupants other than required crewmembers must wear parachutes. However, if an person other than a required crewmember is carried, all occupants, including the crewmembers, must wear the parachutes under this subparagraph.

A field approval may be used to alter the vacum system. This is not a pilot function, but will require the signature of a certificated mechanic with an Inspection Authorization. Using a bypass or simply bypassing the instrument, but leaving it in the panel, does not prevent wear, but increases it.

Gyro instrument experience their greatest damage and wear sitting on the line, being shaken and moved when the wind blows. Another great source of wear is allowing the aircraft to be moved within approximately 45 minutes of shutdown. Few operators are aware of this. As the speed decays and the gyro destabilizes, an enormous amount of wear and potential damage occurs to the gimball bearings.

Something similiar occurs during aerobatic flight or rapid maneuvering with gyros. The force of precession on bearing surfaces wears unevenly, and hastens a premature death of the instrument. Caging the instrument doesn't change this, it only prevents the instrument from tumbling. The damage and wear still occurs.

Most gyros are not capable of flight through loops and rolls without tumbling, or without precession errors. The most common precession error may be induced with a steep or standard rate turn of 180 degrees. Even rapid turn entries can hasten or accelerate wear damage to the ruby bearing surfaces in gyros.

The excerpt from Modern Airmanship is misleading, as it applies to only some gyros.

A series of one turn spins can certainly damage a gyro. However, a one turn spin is still incipient, and doesn't represent effective or proper spin training. Any abrupt maneuvers can damage the gyro. Gyros are delicate, precision instruments. Treat them like powerplants and treat them with care like your life depends on them. It may.

 

[dmspilot00]

Crewmember

Just to clarify, the regulations states that you must have a parachute if carrying a person "other than a crewmember," but does not say "other than a required crewmember." A crewmember is simply a person who is assigned a duty for the flight (FAR 1).

If you are carrying someone that is not a crewmember, then everyone has to wear a parachute.