Center letter: i
Outer letter: a d e h l p
Answers (56):
  helipad
  aide
  aided
  ailed
  allied
  aphid
  applied
  dahlia
  dallied
  deli
  dial
  dialed
  diddle
  diddled
  died
  dill
  dipped
  eddied
  elide
  elided
  hail
  hailed
  hide
  hied
  hill
  hilled
  hippie
  idea
  ideal
  idle
  idled
  laddie
  laid
  lidded
  lied
  lipid
  lipped
  paid
  pail
  pallid
  papilla
  papillae
  phalli
  phial
  piddle
  piddled
  pied
  pile
  piled
  pill
  pilled
  pipe
  piped
  plaid
  plie
  plied