Narrative:

I was acting as an independent contract PIC for a part 91 mission in an aircraft that I was not familiar with. I was flying with the non type-rated sic for the first time; carrying one passenger. I made myself familiar with the aircraft layout and verified the onboard equipment and paperwork were in order. I personally performed the preflight inspection and found the CE550 aircraft to be in good; airworthy condition. As we completed the before start checklist and taxied out; I made myself familiar with the feel of the aircraft. All system passed preflight system checks. On climb out from cno to prb; we began to have problems with our communication radios; communication #2 failed to transmit or receive and communication #1 would receive; but ATC could not hear us when we transmitted. Other aircraft could hear us and transmitted our ATC requests via relay through other aircraft. Since we had no other problems; I decided that it would be prudent to continue to destination on our short 37 min flight plan. In our descent through around 15000 ft MSL; we began having success communicating directly with ATC. We landed without incident and it seemed that the problem was transient as all radios now seemed to work again. As a precaution; the sic; who works for the operator; contacted the owner's maintenance department and reported the problem. As our final destination was iad; I told the operator that I would terminate the trip if the problem recurred and would definitely not to try to enter the washington; dc; area if there was any question as to the reliability of both communication radios. As it seemed that the radios were now working; I assumed the problem was moisture or something transient that resolved itself during our descent. I elected to continue eastbound; now with 2 passenger to our fuel stop in sln. Again; during our climb out from prb; we encountered the same radio problems that we encountered on our first leg. As before we tried to relay through other aircraft and now used the 7600 transponder code to indicate that we had lost our 2-WAY communication capability. We decided to divert to hnd as it was on our flight plan. We had no other indications of system abnormalities and felt safe to use hnd as our diversion point. Again; we landed without incident and during our descent into the las vegas terminal area. After landing at hnd; I insisted that a mechanic check the aircraft before further flight; as it was not apparent that the problem had not resolved itself; but was duplicated while climbing above a certain altitude. The mechanic who was called out removed and 're-racked' all of the communication units in the nose of the plane; removed and reinstalled both communication panels in the cockpit and inspected the avionics for obvious problems the sic told me at that point that both control yokes had recently been removed to facilitate sheet metal work on the cockpit floor. The mechanic said that it was possible that this was the cause of our communication problems. He was unable to reproduce the problem we encountered in-flight. He did find a loose wire on the pilot side hand microphone lead which was grounding out on the cockpit floor. The mechanic repaired the loose wire and operationally checked the pilot hand microphone was working properly. Based on the mechanic's report that he could not duplicate the fault and knowing that we only encountered the problem at high altitude; I elected to not continue the mission eastbound. The operator was left to re-accommodate the passenger; but asked me to return the aircraft to its home base in cno. Having had the aircraft inspected by a mechanic; I felt confident that we would not have additional con problems on our short 36 min flight from hnd to cno. As a precaution; I filed the IFR flight plan at 14000 ft MSL to avoid the altitudes that we had experienced the communication problem at. We encountered intermittent loss of 2-WAY air-to-ground communication on this final leg as well. We again used other aircraft to assist us by relaying to ATC. We again regained full communication capability as we got closer to the ground in our descent. I left the aircraft with the operator at its home base and notified them of the discrepancy. My reason for filing this report is to allow other people to contemplate the problem I was faced with. At what point does a PIC refuse to fly an aircraft with an in-flight problem that cannot be reproduced on the ground? I feel that I made all the decisions correctly based on the information I had at the time; but in hindsight; I should have turned around during the initial climb out on the first leg. I also should not have assumed that the airplane's mechanical condition was resolved just because I got the system working again. Unfamiliarity with the aircraft and my sic contributed to my decision making; which will be more conservative in the future.

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Original NASA ASRS Text

Title: C550 PLT DESCRIBED INTERMITTENT RADIO PROBLEMS DURING SEVERAL SHORT FLIGHTS AND MAINT ATTEMPTS TO RESOLVE THE COM DIFFICULTIES.

Narrative: I WAS ACTING AS AN INDEPENDENT CONTRACT PIC FOR A PART 91 MISSION IN AN ACFT THAT I WAS NOT FAMILIAR WITH. I WAS FLYING WITH THE NON TYPE-RATED SIC FOR THE FIRST TIME; CARRYING ONE PAX. I MADE MYSELF FAMILIAR WITH THE ACFT LAYOUT AND VERIFIED THE ONBOARD EQUIP AND PAPERWORK WERE IN ORDER. I PERSONALLY PERFORMED THE PREFLT INSPECTION AND FOUND THE CE550 ACFT TO BE IN GOOD; AIRWORTHY CONDITION. AS WE COMPLETED THE BEFORE START CHKLIST AND TAXIED OUT; I MADE MYSELF FAMILIAR WITH THE FEEL OF THE ACFT. ALL SYS PASSED PREFLT SYS CHKS. ON CLBOUT FROM CNO TO PRB; WE BEGAN TO HAVE PROBS WITH OUR COM RADIOS; COM #2 FAILED TO XMIT OR RECEIVE AND COM #1 WOULD RECEIVE; BUT ATC COULD NOT HEAR US WHEN WE XMITTED. OTHER ACFT COULD HEAR US AND XMITTED OUR ATC REQUESTS VIA RELAY THROUGH OTHER ACFT. SINCE WE HAD NO OTHER PROBS; I DECIDED THAT IT WOULD BE PRUDENT TO CONTINUE TO DEST ON OUR SHORT 37 MIN FLT PLAN. IN OUR DSCNT THROUGH AROUND 15000 FT MSL; WE BEGAN HAVING SUCCESS COMMUNICATING DIRECTLY WITH ATC. WE LANDED WITHOUT INCIDENT AND IT SEEMED THAT THE PROB WAS TRANSIENT AS ALL RADIOS NOW SEEMED TO WORK AGAIN. AS A PRECAUTION; THE SIC; WHO WORKS FOR THE OPERATOR; CONTACTED THE OWNER'S MAINT DEPT AND RPTED THE PROB. AS OUR FINAL DEST WAS IAD; I TOLD THE OPERATOR THAT I WOULD TERMINATE THE TRIP IF THE PROB RECURRED AND WOULD DEFINITELY NOT TO TRY TO ENTER THE WASHINGTON; DC; AREA IF THERE WAS ANY QUESTION AS TO THE RELIABILITY OF BOTH COM RADIOS. AS IT SEEMED THAT THE RADIOS WERE NOW WORKING; I ASSUMED THE PROB WAS MOISTURE OR SOMETHING TRANSIENT THAT RESOLVED ITSELF DURING OUR DSCNT. I ELECTED TO CONTINUE EBOUND; NOW WITH 2 PAX TO OUR FUEL STOP IN SLN. AGAIN; DURING OUR CLBOUT FROM PRB; WE ENCOUNTERED THE SAME RADIO PROBS THAT WE ENCOUNTERED ON OUR FIRST LEG. AS BEFORE WE TRIED TO RELAY THROUGH OTHER ACFT AND NOW USED THE 7600 XPONDER CODE TO INDICATE THAT WE HAD LOST OUR 2-WAY COM CAPABILITY. WE DECIDED TO DIVERT TO HND AS IT WAS ON OUR FLT PLAN. WE HAD NO OTHER INDICATIONS OF SYS ABNORMALITIES AND FELT SAFE TO USE HND AS OUR DIVERSION POINT. AGAIN; WE LANDED WITHOUT INCIDENT AND DURING OUR DSCNT INTO THE LAS VEGAS TERMINAL AREA. AFTER LNDG AT HND; I INSISTED THAT A MECH CHK THE ACFT BEFORE FURTHER FLT; AS IT WAS NOT APPARENT THAT THE PROB HAD NOT RESOLVED ITSELF; BUT WAS DUPLICATED WHILE CLBING ABOVE A CERTAIN ALT. THE MECH WHO WAS CALLED OUT REMOVED AND 'RE-RACKED' ALL OF THE COM UNITS IN THE NOSE OF THE PLANE; REMOVED AND REINSTALLED BOTH COM PANELS IN THE COCKPIT AND INSPECTED THE AVIONICS FOR OBVIOUS PROBS THE SIC TOLD ME AT THAT POINT THAT BOTH CTL YOKES HAD RECENTLY BEEN REMOVED TO FACILITATE SHEET METAL WORK ON THE COCKPIT FLOOR. THE MECH SAID THAT IT WAS POSSIBLE THAT THIS WAS THE CAUSE OF OUR COM PROBS. HE WAS UNABLE TO REPRODUCE THE PROB WE ENCOUNTERED INFLT. HE DID FIND A LOOSE WIRE ON THE PLT SIDE HAND MIKE LEAD WHICH WAS GNDING OUT ON THE COCKPIT FLOOR. THE MECH REPAIRED THE LOOSE WIRE AND OPERATIONALLY CHKED THE PLT HAND MIKE WAS WORKING PROPERLY. BASED ON THE MECH'S RPT THAT HE COULD NOT DUPLICATE THE FAULT AND KNOWING THAT WE ONLY ENCOUNTERED THE PROB AT HIGH ALT; I ELECTED TO NOT CONTINUE THE MISSION EBOUND. THE OPERATOR WAS LEFT TO RE-ACCOMMODATE THE PAX; BUT ASKED ME TO RETURN THE ACFT TO ITS HOME BASE IN CNO. HAVING HAD THE ACFT INSPECTED BY A MECH; I FELT CONFIDENT THAT WE WOULD NOT HAVE ADDITIONAL CON PROBS ON OUR SHORT 36 MIN FLT FROM HND TO CNO. AS A PRECAUTION; I FILED THE IFR FLT PLAN AT 14000 FT MSL TO AVOID THE ALTS THAT WE HAD EXPERIENCED THE COM PROB AT. WE ENCOUNTERED INTERMITTENT LOSS OF 2-WAY AIR-TO-GND COM ON THIS FINAL LEG AS WELL. WE AGAIN USED OTHER ACFT TO ASSIST US BY RELAYING TO ATC. WE AGAIN REGAINED FULL COM CAPABILITY AS WE GOT CLOSER TO THE GND IN OUR DSCNT. I LEFT THE ACFT WITH THE OPERATOR AT ITS HOME BASE AND NOTIFIED THEM OF THE DISCREPANCY. MY REASON FOR FILING THIS RPT IS TO ALLOW OTHER PEOPLE TO CONTEMPLATE THE PROB I WAS FACED WITH. AT WHAT POINT DOES A PIC REFUSE TO FLY AN ACFT WITH AN INFLT PROB THAT CANNOT BE REPRODUCED ON THE GND? I FEEL THAT I MADE ALL THE DECISIONS CORRECTLY BASED ON THE INFO I HAD AT THE TIME; BUT IN HINDSIGHT; I SHOULD HAVE TURNED AROUND DURING THE INITIAL CLBOUT ON THE FIRST LEG. I ALSO SHOULD NOT HAVE ASSUMED THAT THE AIRPLANE'S MECHANICAL CONDITION WAS RESOLVED JUST BECAUSE I GOT THE SYS WORKING AGAIN. UNFAMILIARITY WITH THE ACFT AND MY SIC CONTRIBUTED TO MY DECISION MAKING; WHICH WILL BE MORE CONSERVATIVE IN THE FUTURE.

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.