Narrative:

While just outside ny TCA, VFR and taking advisories from ny approach, the controller issued me an instruction to 'turn to 290' (my last instruction, from the previous controller was to fly the 11 NM lga DME arc to stay outside TCA). I responded, 'left turn to 290,' and commenced a left turn of about 40 degrees. That turn probably brought me inside the ny TCA and toward lga's final approach path. A turn to 290 degrees should have been a right turn. However, my HSI malfunctioned and showed 290 degrees to the left of my course when the instruction was issued. After perhaps 30 seconds, the controller noticed my left turn and issued me immediate instructions to turn north and descend from 2500-1400'. I wish, particularly, to bring attention to these considerations: 1) equipment. The king HSI in my aircraft is a kcs 55A compass system with 525 indicator. It showed 50 or more degree error with no warning heading flag. After this incident, when I checked it later in flight and on the ground, it showed an error of up to 60 degrees. Throughout the remainder of the flight and until shutdown on the ground the error was present. I still don't know what was wrong, but inaccurate information with no flag seems unacceptably dangerous. I had a previous problem with this system back in the late fall of 1990. The CDI was hanging up as centered when, in fact, the course selected was off to the right or left by some miles. I had this checked out and repaired (dirty slip rings was the diagnosis) early in 1991. With that incident, there was no warning flag either. 2) procedures. I confirmed the instruction, 'turn to 290'--which should have been a right turn--with a reply, 'left turn 290' (emphasis on the word 'left). I did so because a left turn toward the TCA was unusual. I offered the word 'left' as a mild challenge or invitation to check the instruction. In my mind, I thought the turn may have been given for traffic avoidance, spacing, etc. Apparently, the controller did not hear or register my response that I understood his instructions to require a left turn. Perhaps it would be valuable if all turn instructions were given with a direction for the turn; e.g., 'turn left 230,' to give an extra opportunity for confirmation and to avoid mistakes. 1 extra word, 'left' or 'right,' takes very little time. 1) (continued) while the repair was underway on my HSI, I flew the aircraft and flew a practice ILS. With ILS frequency selected to display on the HSI, the G/south needles stayed dead centered the entire time, regardless of where the aircraft way, in fact, on the G/south path. On the ground, the repair shop (in whom I now have low confidence) informed me that they had inadvertently disconnected the wire from the centered G/south needle when the receiver is tuned to an ILS frequency. No warning flag was displayed. If this is true, this appears to be a dangerous peculiarity of the INS. Callback conversation with reporter revealed the following: aircraft is equipped with a wet compass, LORAN and a conventional dg. Missing the error in the HSI was just a simple oversight. Reference the G/south problem, no flag is installed. When the G/south is not received, the fly bars bias out of view. Feels this should have been the case when the wire was not hooked up properly. Agrees the controller use of 'left' or 'right' would probably not solve the problem, but more careful hearback would have helped in this incident. No action has been taken by the FAA reference the TCA penetration, if in fact he penetrates. Mentioned the CDI can hang up in the on course position if the slip rings are dirty, no warning flag. Like to see this a mandatory inspection item.

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Original NASA ASRS Text

Title: HSI MALFUNCTION RESULT IN A LEFT TURN TO 290 DEGREES VERSUS RIGHT TURN. ENTERED TCA.

Narrative: WHILE JUST OUTSIDE NY TCA, VFR AND TAKING ADVISORIES FROM NY APCH, THE CTLR ISSUED ME AN INSTRUCTION TO 'TURN TO 290' (MY LAST INSTRUCTION, FROM THE PREVIOUS CTLR WAS TO FLY THE 11 NM LGA DME ARC TO STAY OUTSIDE TCA). I RESPONDED, 'LEFT TURN TO 290,' AND COMMENCED A LEFT TURN OF ABOUT 40 DEGS. THAT TURN PROBABLY BROUGHT ME INSIDE THE NY TCA AND TOWARD LGA'S FINAL APCH PATH. A TURN TO 290 DEGS SHOULD HAVE BEEN A RIGHT TURN. HOWEVER, MY HSI MALFUNCTIONED AND SHOWED 290 DEGS TO THE LEFT OF MY COURSE WHEN THE INSTRUCTION WAS ISSUED. AFTER PERHAPS 30 SECS, THE CTLR NOTICED MY LEFT TURN AND ISSUED ME IMMEDIATE INSTRUCTIONS TO TURN N AND DSND FROM 2500-1400'. I WISH, PARTICULARLY, TO BRING ATTN TO THESE CONSIDERATIONS: 1) EQUIP. THE KING HSI IN MY ACFT IS A KCS 55A COMPASS SYS WITH 525 INDICATOR. IT SHOWED 50 OR MORE DEG ERROR WITH NO WARNING HDG FLAG. AFTER THIS INCIDENT, WHEN I CHKED IT LATER IN FLT AND ON THE GND, IT SHOWED AN ERROR OF UP TO 60 DEGS. THROUGHOUT THE REMAINDER OF THE FLT AND UNTIL SHUTDOWN ON THE GND THE ERROR WAS PRESENT. I STILL DON'T KNOW WHAT WAS WRONG, BUT INACCURATE INFO WITH NO FLAG SEEMS UNACCEPTABLY DANGEROUS. I HAD A PREVIOUS PROB WITH THIS SYS BACK IN THE LATE FALL OF 1990. THE CDI WAS HANGING UP AS CENTERED WHEN, IN FACT, THE COURSE SELECTED WAS OFF TO THE RIGHT OR LEFT BY SOME MILES. I HAD THIS CHKED OUT AND REPAIRED (DIRTY SLIP RINGS WAS THE DIAGNOSIS) EARLY IN 1991. WITH THAT INCIDENT, THERE WAS NO WARNING FLAG EITHER. 2) PROCS. I CONFIRMED THE INSTRUCTION, 'TURN TO 290'--WHICH SHOULD HAVE BEEN A RIGHT TURN--WITH A REPLY, 'LEFT TURN 290' (EMPHASIS ON THE WORD 'LEFT). I DID SO BECAUSE A LEFT TURN TOWARD THE TCA WAS UNUSUAL. I OFFERED THE WORD 'LEFT' AS A MILD CHALLENGE OR INVITATION TO CHK THE INSTRUCTION. IN MY MIND, I THOUGHT THE TURN MAY HAVE BEEN GIVEN FOR TFC AVOIDANCE, SPACING, ETC. APPARENTLY, THE CTLR DID NOT HEAR OR REGISTER MY RESPONSE THAT I UNDERSTOOD HIS INSTRUCTIONS TO REQUIRE A LEFT TURN. PERHAPS IT WOULD BE VALUABLE IF ALL TURN INSTRUCTIONS WERE GIVEN WITH A DIRECTION FOR THE TURN; E.G., 'TURN LEFT 230,' TO GIVE AN EXTRA OPPORTUNITY FOR CONFIRMATION AND TO AVOID MISTAKES. 1 EXTRA WORD, 'LEFT' OR 'RIGHT,' TAKES VERY LITTLE TIME. 1) (CONTINUED) WHILE THE REPAIR WAS UNDERWAY ON MY HSI, I FLEW THE ACFT AND FLEW A PRACTICE ILS. WITH ILS FREQ SELECTED TO DISPLAY ON THE HSI, THE G/S NEEDLES STAYED DEAD CENTERED THE ENTIRE TIME, REGARDLESS OF WHERE THE ACFT WAY, IN FACT, ON THE G/S PATH. ON THE GND, THE REPAIR SHOP (IN WHOM I NOW HAVE LOW CONFIDENCE) INFORMED ME THAT THEY HAD INADVERTENTLY DISCONNECTED THE WIRE FROM THE CENTERED G/S NEEDLE WHEN THE RECEIVER IS TUNED TO AN ILS FREQ. NO WARNING FLAG WAS DISPLAYED. IF THIS IS TRUE, THIS APPEARS TO BE A DANGEROUS PECULIARITY OF THE INS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: ACFT IS EQUIPPED WITH A WET COMPASS, LORAN AND A CONVENTIONAL DG. MISSING THE ERROR IN THE HSI WAS JUST A SIMPLE OVERSIGHT. REF THE G/S PROB, NO FLAG IS INSTALLED. WHEN THE G/S IS NOT RECEIVED, THE FLY BARS BIAS OUT OF VIEW. FEELS THIS SHOULD HAVE BEEN THE CASE WHEN THE WIRE WAS NOT HOOKED UP PROPERLY. AGREES THE CTLR USE OF 'LEFT' OR 'RIGHT' WOULD PROBABLY NOT SOLVE THE PROB, BUT MORE CAREFUL HEARBACK WOULD HAVE HELPED IN THIS INCIDENT. NO ACTION HAS BEEN TAKEN BY THE FAA REF THE TCA PENETRATION, IF IN FACT HE PENETRATES. MENTIONED THE CDI CAN HANG UP IN THE ON COURSE POS IF THE SLIP RINGS ARE DIRTY, NO WARNING FLAG. LIKE TO SEE THIS A MANDATORY INSPECTION ITEM.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.