Amsterdam - A Dutch parliamentary committee began a long-awaited inquiry yesterday into the 1992 crash of an El-Al cargo plane into a densely populated Amsterdam suburb, seeking to unravel the riddle of the aircraft's load. Repeated low-level investigations have failed to scotch persistent media suggestions of a cover-up. The parliamentary inquiry into the crash, which follows at least two ministerial inquiries, was triggered by revelations in a Dutch newspaper earlier this month that the cargo shipment included 190 litres of dimethyl methylphosphonate, a chemical that experts say is a component of sarin nerve gas.