Errant RPM Indications with HXr
Posted: Fri Sep 28, 2018 5:08 am
Need help resolving an errant RPM indication on my HXr EFIS. System was working fine until today.
Fired up my aircraft and immediately noticed what appeared to be an incorrect RPM reading. First I couldn't get the rpm to 1700 for a mag check let alone to full static power at 2200 rpm. Engine was running smoothly. Pulled out my hand-held indicator and the engine was indeed developing full static rpm - 2250 rpm. Hmm. Reduced power to 1700 as indicated by my hand-held indicator; HXr reading 1490 with the mag switch in the BOTH position.
Switching to LEFT mag as one does in conducting the mag check and noticed the usual 50 RPM drop but the EFIS was still indicating incorrectly - 1450.
When I switched to the RIGHT mag, the indication dropped to ZERO, but would occasionally got to 1700, then back to ZERO. Ordinarily this would be an indication of a lose connection, somewhere. It kept doing this.
Shut down the aircraft and after a period of cooling, checked the right and left mag P stub connections along with the inline resistor connections. All were correct and tight. I also pulled the 25 pin D stub EIS connector and inspected the Rt and Left mag inputs. Nothing out of the ordinary. I'm stumped to put it mildly. The Rt mag appears to be putting out a consistent, although incorrect, reading with no fluctuations.
It appears that the Rt mag may be faulty but not being an A&P and not attuned to mag operations, I'm at a loss.
George
Fired up my aircraft and immediately noticed what appeared to be an incorrect RPM reading. First I couldn't get the rpm to 1700 for a mag check let alone to full static power at 2200 rpm. Engine was running smoothly. Pulled out my hand-held indicator and the engine was indeed developing full static rpm - 2250 rpm. Hmm. Reduced power to 1700 as indicated by my hand-held indicator; HXr reading 1490 with the mag switch in the BOTH position.
Switching to LEFT mag as one does in conducting the mag check and noticed the usual 50 RPM drop but the EFIS was still indicating incorrectly - 1450.
When I switched to the RIGHT mag, the indication dropped to ZERO, but would occasionally got to 1700, then back to ZERO. Ordinarily this would be an indication of a lose connection, somewhere. It kept doing this.
Shut down the aircraft and after a period of cooling, checked the right and left mag P stub connections along with the inline resistor connections. All were correct and tight. I also pulled the 25 pin D stub EIS connector and inspected the Rt and Left mag inputs. Nothing out of the ordinary. I'm stumped to put it mildly. The Rt mag appears to be putting out a consistent, although incorrect, reading with no fluctuations.
It appears that the Rt mag may be faulty but not being an A&P and not attuned to mag operations, I'm at a loss.
George