On the FAA type certicate:
FLOATPLANE - with Edo Model 249-2870 floats (H-391B only) S/N 001 through 045, aircraft structural changes required per Helio modifications No. 5A or No. 13. Float installation per Helio modification No. 15. S/N 046 and up, no structural changes required. Float installation per Helio modification No. 15.
FLOATPLANE (H-391B only, S/N 001 through 031) 2800 lbs., when Helio modification No. 21 incorporated. S/N 032 and up: 3000 lbs.
For Helio 250: FLOATPLANE - with Edo model 582-3430 floats
S/N 2501, 2506 and up. Installation per Helio drawing 250-000-015.
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These are the models certified inside the type certificate. Other models of floats can be STC'd