SMA PLT NARRATES A TALE OF ACFT EQUIP PROBLEMS THAT COMBINED WITH ENRTE WX AND TERMINAL AREA WX CREATED A HIGH IAP ILS BACK COURSE APCH AND LONG LNDG.

Narrative

I WAS BTWN TLH AND MSY. I AM ONLY SLIGHTLY FAMILIAR WITH THE AREA. APCHED MSY FROM GREENE CO VOR OFF AIRWAY BY RNAV. TSTMS BOTH R AND L AND LIGHTNING NEAR ARPT RPTED ON ATIS. THE DIRECTIONAL GYRO FAILED APCHING TCA OR WITHIN TCA AREA. THE LORAN LOST TRACKING FOR A SHORT PERIOD APCHING MSY. ON APCH NEEDLE MAINTAINED WITHIN SCALE WITH LARGE SWINGS; BUT LANDED LONG ON RWY (NEAR FAR END) BECAUSE FINAL APCH WAS HIGH. I FELT THE LACK OF THE DIRECTIONAL GYRO PLUS LIGHTNING IN ALL QUADRANTS REQUIRED. I LAND WITHOUT MISSING THE APCH. AN SMA CAN LOSE CONSIDERABLE ALT QUICKLY. MY CONCERN IS THAT THE APCH WAS DONE POORLY; TOO HIGH AND LNDG WAS LONG. I WAS CONCERNED THAT MISSING THE APCH WOULD PUT THE PLANE IN SEVERE WX TO THE S OF THE ARPT. THE APCH WAS HIGH BECAUSE OF DIFFICULTY IN READING LOWEST MIN ON APCH PLATE BECAUSE OF THE USE OF ONLY THE MAGNETIC COMPASS AND LOC TO MAKE THE APCH; PLUS RAIN ENTERING THE CABIN AND TURB; I WAS ONLY SLIGHTLY FAMILIAR WITH NEW ORLEANS AND THE AREA I HAD JUST TRAVELED THROUGH. IT IS DIFFICULT TO SUGGEST A WAY TO AVOID THE PROBLEM BECAUSE OF TURB IN FLT BECAUSE 'ATIS' COULD NOT BE HEARD TO DETERMINE THE APCH. THE GYRO MADE THE APCH DIFFICULT. POSSIBLY NOTIFYING APCH OF THE GYRO PROBLEM MIGHT HAVE HELPED. TOO MUCH SEEMED TO BE HAPPENING TO THINK ABOUT NOTIFYING APCH CTL AND IT MAY NOT HAVE HELPED. OTHER NEW EQUIP IN THE PLANE (STORM DETECTOR) WAS ALSO MALFUNCTIONING (THOUGH I DID NOT REALIZE IT). NO INCIDENT OTHER THAN VERY LONG LNDG ON RWY.