# AD 52-26-01: Stabilizer Spar Web

- Type: Airworthiness directive
- Status: Current
- Products: Sierra Hotel Aero Navion (Army L-17A), Navion A (Army L-17B and L-17C) and Navion B
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 746 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/0DB9D88382B3783F86256A56006FAB28.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/52-26-01

## The airworthiness directive

52-26-01 NAVION: Applies to All Models, Serial Numbers NAV-4-2 and Subsequent.

Compliance required as indicated.

Inspect as soon as practical, but not later than February 1, 1953, and at 100-hour intervals thereafter the area in the vicinity of the stabilizer fuselage attachment for cracks. Particular attention should be given to the stabilizer spar web (gusset) immediately outboard of the root rib and the fuselage attaching fitting. If cracks are found in the fuselage fitting, P/N 143-31004-13, the entire part should be replaced. Cracks in the root rib may be repaired in accordance with CAM No. 18. Cracks in the spar web (gusset) require the replacement of the gusset with a new part made in accordance with Figure 2.

AD 52-26-01

Periodic inspections of stabilizer spar web only may be discontinued after installation of new gussets.

(Ryan Navion Field Service Bulletin No. 17 dated September 28, 1952, 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 3 of 8 models: Navion B, Navion (Army L-17A), Navion A (Army L-17B and L-17C)

## 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: 746 (746 by airframe model, 0 by engine model)
- Makers: Ryan 353, North American 252, Navion 141

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)
- [North American NAVION B](https://openairdocs.org/model/north-american-navion-b): 3 aircraft (airframe model)

All 9 models: https://openairdocs.org/ad/52-26-01/models.md
Every aircraft: https://openairdocs.org/ad/52-26-01/aircraft.md

Its text cites no advisory circulars or STCs.

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