Narrative:

I am a newly IFR rated private pilot with 4.5 hours of actual IMC, 49.3 hours simulated instrument, 180.5 hours PIC time. I was PIC of a PA28-140 at elmdale airport, (6f4) abilene, tx. We departed elmdale and I reported airborne as I turned to 120 degree heading and continued climbing. We were quickly in thick IMC. Approach vectored me around to the north and we were on top of the overcast at about 3800 ft and I continued to climb and level out at 4000 ft. Approach vectored me onto the 020 degree radial off of tuscola, tqa, VOR. I was cleared to descend to 3100 ft and was advised I was 7 mi from FAF, bowie intersection. As I descended into the clouds I was busy controling the airplane and keeping up my scan. Approach advised me to expect clearance to runway 17R. The airplane descended below the 3100 ft I was cleared for. I first noticed that I was at 2600 ft because I had descended below the cloud. I went full power and began climbing, but was at indicated 2500 ft before I could reverse my descent. I noticed the prison water tower and knew I was well above any obstructions so our safety was not so much a concern to me at that point as the fact that I knew I had inadvertently busted a minimum altitude. I set myself up for trouble when I changed the way I had been trained to trim back to 80 mph IAS at 2200 RPM while maneuvering for an approach. Approach advised me with a low altitude alert and I advised I was already correcting. Approach told me to turn right to 270 degree heading and climb and maintain 4000 ft and advised they could not continue the approach since my transponder had stopped working. I turned to 270 and climbed to 4000 feet. I advised approach we were trying to fix the transponder problem and also mentioned I had just had it worked on. I now had broken sky below and I advised approach I wanted to get back on the ground to troubleshoot the transponder problem as it was not a blown fuse. I advised I would like to cancel IFR clearance and get a special VFR clearance for direct flight back to elmdale below the overcast. Approach asked for a position report as we maneuvered for a left downwind. We landed and reported that to approach. The next day I performed some troubleshooting as I hold airframe and power plant mechanic licenses. I found the positive lead to the KT-76 transponder also fed the LORAN and had a cold solder joint to the fuse holder at the busbar. This cold solder joint was determined to be the cause of the intermittent operation of the transponder. I made appropriate repairs. In order to prevent going below assigned altitude on an approach I am going to improve my scan with more practice. I am also going to slow down to the low cruise (80 mph at 2200 RPM) before reaching the inbound radial or localizer. This slows things down for me as a beginner and makes it simpler for me.

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Original NASA ASRS Text

Title: LOW IFR TIME PA28 PLT DSNDS FROM ASSIGNED ALT WHEN ON APCH TO ABI DUE TO LOSS OF SITUATIONAL AWARENESS AND LESS SEVERE EQUIP PROBS.

Narrative: I AM A NEWLY IFR RATED PVT PLT WITH 4.5 HRS OF ACTUAL IMC, 49.3 HRS SIMULATED INST, 180.5 HRS PIC TIME. I WAS PIC OF A PA28-140 AT ELMDALE ARPT, (6F4) ABILENE, TX. WE DEPARTED ELMDALE AND I RPTED AIRBORNE AS I TURNED TO 120 DEG HDG AND CONTINUED CLBING. WE WERE QUICKLY IN THICK IMC. APCH VECTORED ME AROUND TO THE N AND WE WERE ON TOP OF THE OVCST AT ABOUT 3800 FT AND I CONTINUED TO CLB AND LEVEL OUT AT 4000 FT. APCH VECTORED ME ONTO THE 020 DEG RADIAL OFF OF TUSCOLA, TQA, VOR. I WAS CLRED TO DSND TO 3100 FT AND WAS ADVISED I WAS 7 MI FROM FAF, BOWIE INTXN. AS I DSNDED INTO THE CLOUDS I WAS BUSY CTLING THE AIRPLANE AND KEEPING UP MY SCAN. APCH ADVISED ME TO EXPECT CLRNC TO RWY 17R. THE AIRPLANE DSNDED BELOW THE 3100 FT I WAS CLRED FOR. I FIRST NOTICED THAT I WAS AT 2600 FT BECAUSE I HAD DSNDED BELOW THE CLOUD. I WENT FULL PWR AND BEGAN CLBING, BUT WAS AT INDICATED 2500 FT BEFORE I COULD REVERSE MY DSCNT. I NOTICED THE PRISON WATER TWR AND KNEW I WAS WELL ABOVE ANY OBSTRUCTIONS SO OUR SAFETY WAS NOT SO MUCH A CONCERN TO ME AT THAT POINT AS THE FACT THAT I KNEW I HAD INADVERTENTLY BUSTED A MINIMUM ALT. I SET MYSELF UP FOR TROUBLE WHEN I CHANGED THE WAY I HAD BEEN TRAINED TO TRIM BACK TO 80 MPH IAS AT 2200 RPM WHILE MANEUVERING FOR AN APCH. APCH ADVISED ME WITH A LOW ALT ALERT AND I ADVISED I WAS ALREADY CORRECTING. APCH TOLD ME TO TURN R TO 270 DEG HDG AND CLB AND MAINTAIN 4000 FT AND ADVISED THEY COULD NOT CONTINUE THE APCH SINCE MY XPONDER HAD STOPPED WORKING. I TURNED TO 270 AND CLIMBED TO 4000 FEET. I ADVISED APPROACH WE WERE TRYING TO FIX THE TRANSPONDER PROBLEM AND ALSO MENTIONED I HAD JUST HAD IT WORKED ON. I NOW HAD BROKEN SKY BELOW AND I ADVISED APCH I WANTED TO GET BACK ON THE GND TO TROUBLESHOOT THE XPONDER PROB AS IT WAS NOT A BLOWN FUSE. I ADVISED I WOULD LIKE TO CANCEL IFR CLRNC AND GET A SPECIAL VFR CLRNC FOR DIRECT FLT BACK TO ELMDALE BELOW THE OVCST. APCH ASKED FOR A POS RPT AS WE MANEUVERED FOR A L DOWNWIND. WE LANDED AND RPTED THAT TO APCH. THE NEXT DAY I PERFORMED SOME TROUBLESHOOTING AS I HOLD AIRFRAME AND POWER PLANT MECH LICENSES. I FOUND THE POSITIVE LEAD TO THE KT-76 XPONDER ALSO FED THE LORAN AND HAD A COLD SOLDER JOINT TO THE FUSE HOLDER AT THE BUSBAR. THIS COLD SOLDER JOINT WAS DETERMINED TO BE THE CAUSE OF THE INTERMITTENT OP OF THE XPONDER. I MADE APPROPRIATE REPAIRS. IN ORDER TO PREVENT GOING BELOW ASSIGNED ALT ON AN APCH I AM GOING TO IMPROVE MY SCAN WITH MORE PRACTICE. I AM ALSO GOING TO SLOW DOWN TO THE LOW CRUISE (80 MPH AT 2200 RPM) BEFORE REACHING THE INBOUND RADIAL OR LOC. THIS SLOWS THINGS DOWN FOR ME AS A BEGINNER AND MAKES IT SIMPLER FOR ME.

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.