Date: 201205
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Aileron Control System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Confusion; Situational Awareness; Troubleshooting
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: General Maintenance Action; General Flight Cancelled / Delayed
Contributing factors: Procedure; MEL; Manuals; Aircraft; Chart Or Publication; Human Factors
Primary problem: MEL

Narrative: This aircraft had an MEL for a ROLL CONTROL DISC message that had appeared on an earlier flight.  Upon review of the MEL; I found the wording to be confusing and am writing this report to bring light to the issue that I have with the MEL 27-11-12-1.  These are the remarks taken from the MEL: O) May be inoperative provided: a) Both control wheels are verified to  be connected before each flight; b) Autopilot channels are considered inoperative; and c) Aircraft is not operated in RVSM airspace and is not considered to be RVSM compliant.  Does 'a)' refer to the yokes being connected to each other? Or that each yoke should be connected to it's onside aileron?  To compound the issue; under the Flight Crew Operating Procedure; there is this procedure; which as it is written; makes no sense whatsoever: Verify that both control wheels are connected by performing the following check:Roll Control Mechanical Interconnection check: 1. Hold the left wheel in the neutral position.2. Try to turn the right control wheel to the left and the right. 3. Verify that there is no relative movement between the control wheels. If relative movement between both  control wheels is not observed then the aileron mechanical interconnection is connected.  I assume by the English language definition of 'relative' it means 'related'; as in; if one moves; then the other should move relative / with it.  So how is it that if I move one yoke; and the other one is NOT OBSERVED to move (per the procedure);  that they are 'connected.' Surely the opposite is true... if one moves; and the other one doesn't; then they are NOT connected? I called Maintenance Control; and brought up my concerns; but the Maintenance Controller must of thought I was an idiot; because he tried to explain to me what the procedure meant. However; what he said and what the  procedure reads are two completely different things. His explanation to me was exactly what I thought the  procedure SHOULD be written as; but [that] is not how it is written. I consider myself of average intellect at worst; but this one makes no sense to me based on the system knowledge presented to us.  It is written that the Captain's yoke; controls only the left aileron; and the right aileron is only on the First Officer's (F/O) yoke.  The Roll Interconnection between the two yokes below the cockpit floor is what allows both yokes to control both ailerons. So naturally; when I see that the Roll Control Disconnect has been MEL'd; then I  would expect the system to operate as two different systems. Captain on the left; F/O on the right with no relative movement from one yoke to the other. We went along with what the Maintenance Controller said; and what we; as a Flight crew; determined to be the safest and most logical interpretation of the MEL; but this  report is again [written] to surface the discrepancy and poor wording of MEL 27-11-12-1.  Can you tell me what the actual purpose of this MEL is?  Is it to allow a plane with a broken ROLL CONTROL interconnection to continue flying with the Captain using the left aileron and the F/O using the right aileron; or is it a condition where you are assuming you have a spurious EICAS message and are supposed to verify that everything works normally?  The flight proceeded normally without using the Autopilot and Non-Reduced Vertical Separation Minima (RVSM); as per the MEL direction. (the only two parts of it that I actually understood). Explain to me how I read the MEL wrong; or change the wording of the MEL to better explain the reason and method of using this particular MEL.

Callback: Reporter stated he was told that he 'misunderstood' the term 'Relative' as the term is applied to the Maintenance procedures in the Embraer MEL.  The reference to 'No Relative Movement' apparently means no difference in Control Yoke rotation between the Captain's and First Officer's (F/O) control yokes.  That is; the Captain's left input is followed by the F/O's left wheel rotation.  IF the F/O's wheel/yoke does not follow the Captain's yoke roll movement; than that; is considered 'Relative Movement' being observed.  Not when movement of both yokes is synchronous with each other. Reporter stated he still believes Embraer's use of the term 'Relative' is not consistent with common understanding by many pilots of what the term 'relative to' means.



Synopsis: An ERJ-170 Captain reports on the confusion surrounding the term 'No Relative Movement' used in the Embraer MEL 27-11-12 Maintenance Procedures for deferral of a 'ROLL CONTROL DISC' EICAS message on their ERJ-170  aircraft.