# AD 59-17-05: Horizontal Tail Spar Fitting

- Type: Airworthiness directive
- Status: Current
- Products: Helio H-391B and H-395 (USAF L-28A or U-10B)
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 32 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/0375C3CFE0EA493A86256A38005ED799.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/59-17-05

## The airworthiness directive

59-17-05 HELIO: Applies to All Model H-391B Aircraft Except Serial Numbers 093, 094, and 098; and Model H-395, Serial Numbers 502 Through 510.

Compliance required as indicated.

Within the next 10 hours unless already accomplished inspect the horizontal tail front spar splice plate, P/N 391-020-305, for cracks around all bolt holes and the 2.0-inches diameter lightening hole. If cracks are found, the fitting should be replaced with an identically dimensioned part 0.063-inch 4130 steel. If no cracks are found the original aluminum fitting shall be inspected at each 25 hours thereafter until the next 100-hour inspection or October 1, 1959, whichever occurs first, when it must be replaced with a steel part.

(Helio Service Bulletin No. 21 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 2 of 9 models: H-395 (USAF L-28A or U-10B), 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: 32 (32 by airframe model, 0 by engine model)
- Makers: Helio 32

Models with the most aircraft:

- [Helio H-391B](https://openairdocs.org/model/helio-h-391b): 16 aircraft (airframe model)
- [Helio H-395](https://openairdocs.org/model/helio-h-395): 16 aircraft (airframe model)

All 2 models: https://openairdocs.org/ad/59-17-05/models.md
Every aircraft: https://openairdocs.org/ad/59-17-05/aircraft.md

Its text cites no advisory circulars or STCs.

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