Narrative:

I have noticed a pattern of mechanical failures on the crj 100/200 that may merit further investigation. The typical scenario is that both adfs will present a course needle accompanied with good audio identification of the stations. However; the needles do not point to the station. They usually point toward the wingtip area; plus or minus 20 degrees or so. When passing over a station; passage will cause the needles to oscillate and point in a different direction; but not at the station. I have seen more than a dozen airplanes with this issue. The last one was on saturday of october 2006. The next day I operated the aircraft with the adfs deferred into lga. If not for the deferral; on departure; due to a temporary relocation of the lga VOR; I would have used the peth NDB radial to determine the turn point on the single engine departure (reference chart 10-7) and who knows where the course would have pointed. Seems that the navigation systems of this aircraft being quite good along with the lack of use of adfs in general; combines to cause this type of problem to be overlooked. I have noted at least 12 aircraft with the problem. I have not recorded all of the aircraft with the problem - there are probably 6 more aircraft that I did not record. Suffice it to say that if someone actually tried to conduct NDB operations in the wrong situation; the results could be disastrous.callback conversation with reporter revealed the following information: the reporter stated the audio function of the ADF systems work fine but the needles usually point toward the wingtips plus or minus 20 degrees and when passing over a station the needles oscillate and point in a different direction but not at the station. The reporter related the lga departure where use of the NDB would have been used but was alerted by the ADF systems being deferred as inoperative. What concerns the reporter is during the time the needles are pointing at the wing tips there is no failure warning on the primary flight displays or the multi function displays.

Google
 

Original NASA ASRS Text

Title: A CRJ200 CAPT ALLEGES INADEQUATE MAINT SUPPORT OF ADF SYSTEMS. REPORTEDLY; BOTH ADF SYSTEMS WILL HAVE GOOD AUDIO OF THE STATIONS; BUT THE COURSE NEEDLES DO NOT POINT TO THE STATION. CAPT CLAIMS 12 ACFT WITH DEFECTIVE SYSTEMS.

Narrative: I HAVE NOTICED A PATTERN OF MECHANICAL FAILURES ON THE CRJ 100/200 THAT MAY MERIT FURTHER INVESTIGATION. THE TYPICAL SCENARIO IS THAT BOTH ADFS WILL PRESENT A COURSE NEEDLE ACCOMPANIED WITH GOOD AUDIO ID OF THE STATIONS. HOWEVER; THE NEEDLES DO NOT POINT TO THE STATION. THEY USUALLY POINT TOWARD THE WINGTIP AREA; PLUS OR MINUS 20 DEGS OR SO. WHEN PASSING OVER A STATION; PASSAGE WILL CAUSE THE NEEDLES TO OSCILLATE AND POINT IN A DIFFERENT DIRECTION; BUT NOT AT THE STATION. I HAVE SEEN MORE THAN A DOZEN AIRPLANES WITH THIS ISSUE. THE LAST ONE WAS ON SATURDAY OF OCTOBER 2006. THE NEXT DAY I OPERATED THE ACFT WITH THE ADFS DEFERRED INTO LGA. IF NOT FOR THE DEFERRAL; ON DEP; DUE TO A TEMPORARY RELOCATION OF THE LGA VOR; I WOULD HAVE USED THE PETH NDB RADIAL TO DETERMINE THE TURN POINT ON THE SINGLE ENGINE DEPARTURE (REFERENCE CHART 10-7) AND WHO KNOWS WHERE THE COURSE WOULD HAVE POINTED. SEEMS THAT THE NAVIGATION SYSTEMS OF THIS ACFT BEING QUITE GOOD ALONG WITH THE LACK OF USE OF ADFS IN GENERAL; COMBINES TO CAUSE THIS TYPE OF PROB TO BE OVERLOOKED. I HAVE NOTED AT LEAST 12 ACFT WITH THE PROB. I HAVE NOT RECORDED ALL OF THE ACFT WITH THE PROB - THERE ARE PROBABLY 6 MORE ACFT THAT I DID NOT RECORD. SUFFICE IT TO SAY THAT IF SOMEONE ACTUALLY TRIED TO CONDUCT NDB OPERATIONS IN THE WRONG SITUATION; THE RESULTS COULD BE DISASTROUS.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE AUDIO FUNCTION OF THE ADF SYSTEMS WORK FINE BUT THE NEEDLES USUALLY POINT TOWARD THE WINGTIPS PLUS OR MINUS 20 DEGS AND WHEN PASSING OVER A STATION THE NEEDLES OSCILLATE AND POINT IN A DIFFERENT DIRECTION BUT NOT AT THE STATION. THE RPTR RELATED THE LGA DEP WHERE USE OF THE NDB WOULD HAVE BEEN USED BUT WAS ALERTED BY THE ADF SYSTEMS BEING DEFERRED AS INOPERATIVE. WHAT CONCERNS THE RPTR IS DURING THE TIME THE NEEDLES ARE POINTING AT THE WING TIPS THERE IS NO FAILURE WARNING ON THE PRIMARY FLT DISPLAYS OR THE MULTI FUNCTION DISPLAYS.

Data retrieved from NASA's ASRS site as of January 2009 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.