The DC-7, 4193 lb (1902 kg) overloaded, entered an uncontrolled descent and crashed into the sea, after the no. 2 engine failed and the no. 3 engine lost power. The engine failure resulted from inadequate maintenance and inspection and previous damage (taxiing accident Dec. 2, 1972). The Flight Engineer was unqualified for the DC-7. Baseball player Roberto Clemente, 38, was killed in the accident. Clemente was on a relief mission to deliver supplies for earthquake victims in Nicaragua. PROBABLE CAUSE: powerplant – engine structure: master and connecting rods powerplant – engine structure: cylinder assembly powerplant – engine structure: piston,piston rings miscellaneous acts,conditions – excessive-wear/play personnel – maintenance,servicing,inspection: inadequate maintenance and inspection pilot in command – inadequate preflight preparation and/or planning FACTORS: personnel – operational supervisory personnel: deficiency,company maintained eqpmt,services,regulation miscellaneous acts,conditions – improperly loaded aircraft-weight-and/or c.g. miscellaneous acts,conditions – previous damage miscellaneous acts,conditions – aircraft came to rest in water