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Reporter protests inaccurate data in weight and balance papers in old aircraft and approved FAA manual for that aircraft type, model, year.
| Attributes | |
| ACN | 151754 |
| Time | |
| Date | 199007 |
| Day | Mon |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : slk |
| State Reference | NY |
| Altitude | agl bound lower : 0 agl bound upper : 0 |
| Aircraft 1 | |
| Controlling Facilities | artcc : zny |
| Operator | general aviation : personal |
| Make Model Name | Small Aircraft |
| Flight Phase | ground : preflight |
| Flight Plan | None |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : commercial |
| ASRS Report | 151754 |
| Events | |
| Anomaly | other anomaly other |
| Independent Detector | other other : unspecified |
| Resolutory Action | none taken : anomaly accepted |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
I installed floats on an small aircraft and while preparing the weight and balance papers found that the FAA type certificate (#1a2 revision 34) states that the datum is the wing leading edge, and the FAA approved flight manual, dated 10/1/54, with revisions, states that the datum is 60' ahead of the wing leading edge. Among the aircraft records were some figures references to 1 datum, and others to the other, both legally, but the potential exists for grossly incorrect weight and balance status determinations as a result of this inconsistency. FAA and mfr should agree on what the datum really is, and should take steps to ensure that owners, operators and maintenance personnel are aware of the problem. Re: serial # applicability, the flight manual I have is specifically for the aircraft I'm working on, a 1983 model. Callback conversation with reporter revealed the following: with the datum difference as much as 60' when the weight and balance is calculated, it becomes readily apparent which datum point should be used. In this case, it was not a problem; but, when datum line is only slightly different (which is not uncommon), one must experiment carefully to determine the correct datum point to use.
Original NASA ASRS Text
Title: REPORTER PROTESTS INACCURATE DATA IN WEIGHT AND BALANCE PAPERS IN OLD ACFT AND APPROVED FAA MANUAL FOR THAT ACFT TYPE, MODEL, YEAR.
Narrative: I INSTALLED FLOATS ON AN SMA AND WHILE PREPARING THE WT AND BAL PAPERS FOUND THAT THE FAA TYPE CERTIFICATE (#1A2 REVISION 34) STATES THAT THE DATUM IS THE WING LEADING EDGE, AND THE FAA APPROVED FLT MANUAL, DATED 10/1/54, WITH REVISIONS, STATES THAT THE DATUM IS 60' AHEAD OF THE WING LEADING EDGE. AMONG THE ACFT RECORDS WERE SOME FIGURES REFERENCES TO 1 DATUM, AND OTHERS TO THE OTHER, BOTH LEGALLY, BUT THE POTENTIAL EXISTS FOR GROSSLY INCORRECT WT AND BAL STATUS DETERMINATIONS AS A RESULT OF THIS INCONSISTENCY. FAA AND MFR SHOULD AGREE ON WHAT THE DATUM REALLY IS, AND SHOULD TAKE STEPS TO ENSURE THAT OWNERS, OPERATORS AND MAINT PERSONNEL ARE AWARE OF THE PROB. RE: SERIAL # APPLICABILITY, THE FLT MANUAL I HAVE IS SPECIFICALLY FOR THE ACFT I'M WORKING ON, A 1983 MODEL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: WITH THE DATUM DIFFERENCE AS MUCH AS 60' WHEN THE WT AND BAL IS CALCULATED, IT BECOMES READILY APPARENT WHICH DATUM POINT SHOULD BE USED. IN THIS CASE, IT WAS NOT A PROB; BUT, WHEN DATUM LINE IS ONLY SLIGHTLY DIFFERENT (WHICH IS NOT UNCOMMON), ONE MUST EXPERIMENT CAREFULLY TO DETERMINE THE CORRECT DATUM POINT TO USE.
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.