# AD 59-06-04: Hydraulic Actuating Cylinders

- Type: Airworthiness directive
- Status: Current
- Products: Sierra Hotel Aero Navion (Army L-17A), Navion A (Army L-17B and L-17C), Navion B and Navion D
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 754 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/E2404548232346DC86256A56006FCD0C.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/59-06-04

## The airworthiness directive

59-06-04 NAVION: Tusco Corporation (Navion) Applies to All Models.

Several failures of hydraulic actuating cylinders have occurred causing the loss of the use of the flaps and the landing gear to collapse.

To prevent further difficulties of this nature, the following items must be accomplished by May 1, 1959, and at each periodic inspection thereafter.

  (1) Inspect the flap and landing gear actuating cylinders for cracks. If any cracks appear, the cylinder must be replaced.

  (2) Determine, by means of a hydraulic gage, that the hydraulic system pressure relief valve is adjusted to 1125+25, -0 p.s.i. Excessive pressures could cause damage to the components of the system.

  (3) Hydraulic fluid restrictors are required in the nose gear lines, Serial Numbers 1271 and subsequent, main gear lines, Serial Numbers 1790 and subsequent, and flap lines, all serial numbers.

  (4) Inspect the linkage adjustments of the landing gear bungee springs and the flap stops anddetermine that they have been properly adjusted in accordance with appropriate service manuals.

(Tusco Corporation Service Letter No. 79 dated December 23, 1958, covers this same subject.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A-782](https://openairdocs.org/tcds/A-782): Sierra Hotel Aero Inc.; names 4 of 8 models: Navion B, Navion (Army L-17A), Navion A (Army L-17B and L-17C), Navion D

## 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: 754 (754 by airframe model, 0 by engine model)
- Makers: Ryan 355, North American 253, Navion 146

Models with the most aircraft:

- [North American NAVION](https://openairdocs.org/model/north-american-navion): 203 aircraft (airframe model)
- [Ryan NAVION](https://openairdocs.org/model/ryan-navion): 170 aircraft (airframe model)
- [Ryan NAVION A](https://openairdocs.org/model/ryan-navion-a): 115 aircraft (airframe model)
- [Navion NAVION A](https://openairdocs.org/model/navion-navion-a): 99 aircraft (airframe model)
- [Ryan NAVION B](https://openairdocs.org/model/ryan-navion-b): 68 aircraft (airframe model)
- [North American NAVION A](https://openairdocs.org/model/north-american-navion-a): 46 aircraft (airframe model)
- [Navion NAVION B](https://openairdocs.org/model/navion-navion-b): 42 aircraft (airframe model)
- [Navion NAVION D](https://openairdocs.org/model/navion-navion-d): 5 aircraft (airframe model)
- [North American NAVION B](https://openairdocs.org/model/north-american-navion-b): 3 aircraft (airframe model)
- [Ryan NAVION D](https://openairdocs.org/model/ryan-navion-d): 2 aircraft (airframe model)
- [North American NAVION D](https://openairdocs.org/model/north-american-navion-d): 1 aircraft (airframe model)

All 12 models: https://openairdocs.org/ad/59-06-04/models.md
Every aircraft: https://openairdocs.org/ad/59-06-04/aircraft.md

Its text cites no advisory circulars or STCs.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.