You are referring to 1 Peter 3.18ff but I have to disagree with you.
I do not think this passage is saying Jesus went to preach the gospel to people who had already died - this would mean people could be saved after death. I do not this passage means Jesus went to the place of the dead at all, but even if He did (and some do believe this is what it says), he went to proclaim his victory to the unsaved and to the fallen angels. Others believe this passage is saying that Christ was preaching through Moses to those who were disobedient and did not listen to the warnings to repent.
18For Christ also died for sins once for all, the just for the unjust, so that He might bring us to God, having been put to death in the flesh, but made alive in the spirit;
19in which also He went and made proclamation to the spirits now in prison,
20who once were disobedient, when the patience of God kept waiting in the days of Noah, during the construction of the ark, in which a few, that is, eight persons, were brought safely through the water.
21Corresponding to that, baptism now saves you--not the removal of dirt from the flesh, but an appeal to God for a good conscience--through the resurrection of Jesus Christ, 22who is at the right hand of God, having gone into heaven, after angels and authorities and powers had been subjected to Him.
Here is Matthew Henry's commentary on this:
If Christ could not be freed from sufferings, why should Christians think to be so? God takes exact notice of the means and advantages people in all ages have had. As to the old world, Christ sent his Spirit; gave warning by Noah. But though the patience of God waits long, it will cease at last. And the spirits of disobedient sinners, as soon as they are out of their bodies, are committed to the prison of hell, where those that despised Noah's warning now are, and from whence there is no redemption. Noah's salvation in the ark upon the water, which carried him above the floods, set forth the salvation of all true believers.
There is no second chance after death, in the OT or the NT (Heb. 9.27)
Also, why do you say David is in hell? (Keep in mind that often the word translated as "hell" in the Bible means the grave).