# AD 57-25-02: Fin Spar Inspection

- Type: Airworthiness directive
- Status: Current
- Products: Helio H-391B
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 16 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/BE4F86AB7C81A40786256A38005ED40D.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/57-25-02

## The airworthiness directive

57-25-02 HELIO: Applies to Model H-391B Aircraft Serial Numbers 001 Through 055.

Compliance required as indicated.

Cracks have been found in the fin front spar underneath the steel attachment fittings holding the stabilizer to the fin. Cracks were also discovered in the flanges of the fins nose ribs second and third from the bottom. To preclude possible failure of the fin spar, the following inspections and rework are required:

1. Aircraft with less than 400 hours total time.

  (a) Inspect visually for cracks the fin front spar and lower nose ribs within the next 100 hours of operation and every 100 hours thereafter until reinforced as described in Helio Service Bulletin No. 17 or equivalent.

  (b) If cracks are found they must be stopdrilled and the parts reinforced prior to further flight.

  (c) If no cracks are found reinforcement of the fin front spar and lower nose ribs attachments is required prior to the accumulation of 400 hours total time.2. Aircraft having 400 hours or more total time.

  (a) Visual inspection and reinforcement are required within the next 25 hours flight time. If any cracks are found, they should be stop-drilled prior to adding the reinforcements.

(Helio Service Bulletin No. 17 covers this subject.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1A8](https://openairdocs.org/tcds/1A8): Helio Alaska Inc.; names 1 of 9 models: H-391B

## Registered aircraft it may apply to (OpenAirDocs)

Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment.

- Aircraft: 16 (16 by airframe model, 0 by engine model)
- Makers: Helio 16

Models with the most aircraft:

- [Helio H-391B](https://openairdocs.org/model/helio-h-391b): 16 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/57-25-02/models.md
Every aircraft: https://openairdocs.org/ad/57-25-02/aircraft.md

Its text cites no advisory circulars or STCs.

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