An example of the weight estimating problem was the spacecraft hatch. When the decision was made in March 1967 to incorporate a new hatch, the net weight increase was estimated at 185 kilograms, but calculations indicated that this increase was actually 558 kilograms. Neither of these numbers included the additional ballast, which doubled the required weight. Clearly weight estimates were inadequate, making a workable weight control program impossible. North American was requested to take immediate action to bring the weight problem under control. A letter in a similar vein was sent by C. H. Bolender, ASPO LM Manager, to J. G. Gavin, Jr., Grumman Aircraft Engineering Corp.