ALTDEV ALT OVERSHOT SUSPECTED BY ARTCC RADAR CTLR DURING RADAR MONITORING OF AN ACR WDB FRT ACFT IN DSCNT PROC.

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THIS RPT CONCERNS A PROBLEM THAT SURFACED AFTER LNDG AT LAX. THE FLT; ALL CARGO. THE ENTIRE FLT WAS UNEVENTFUL; EXCEPT THAT THE PREFLT WAS EXTENSIVE DUE TO LIGHTNING STRIKES ON THE PREVIOUS LEG. THE ONLY DAMAGE DUE TO THE LIGHTNING DISCOVERED IN ANC CONCERNED A FAILURE OF THE #2 HF; AND EVENTUALLY THE ACFT WAS RELEASED FOR FLT. AFTER DEP FROM ANC CTR ASKED US TO VERIFY OUR ALT SINCE THIS HAPPENED AFTER LEVEL OFF IT SEEMED A LITTLE ODD BUT ATC DID NOT ELABORATE ON THE REQUEST. ON ARR INTO LAX WE WERE ORIGINALLY CLRED FOR THE 'PROFILE DSCNT' BUT WERE VECTORED OFF THE ARR. WE WERE CLRED OUT OF 13000 FT FOR 11000 FT AND DURING THAT DSCNT LAX CTR ASKED US IF WE WERE AT '10-8.' AT THAT TIME WE WERE PASSING 11100 AND IN THE PROCESS OF LEVELING OFF AT 11000. WE RPTED THE 11100 FT READING AND ATC MADE NO COMMENT. AFTER THE UNEVENTFUL APCH AND LNDG; WE WERE TOLD TO CONTACT CTR; WHICH WE DID. LAX CTR SAID THEY SHOWED US AT 8500 FT THEN CLBING QUICKLY BACK TO 11000 FT AND THAT THIS 'DEV' HAD CAUSED THEM TO VECTOR DEPARTING TFC. WE NEVER DSNDED TO AN 8500 FT ALT AND NEVER CLBED FROM A LOWER TO HIGHER ALT DURING THE ARR; MAINT REMOVED THE TRANSPONDER AND FLT DATA RECORDER AND REPLACED THEM BEFORE THE ACFT WAS RELEASED. WE ASSUME AN ALT READOUT PROBLEM POSSIBLY DUE TO THE LIGHTNING STRIKES.