Spray Tank Mod ApprovalsSpray Tank Mod Approvals

Design Delegation Holders Seminar Oct 2005

by Jack Stanton

Team Leader Continuing Airworthiness Civil Aviation Authority

Recent Ag Helo AccidentsRecent Ag Helo Accidents

ZK-HSF UH-1 23 April 04 ZK-HWP R22 Nov 2004

Incidents: June 2005 R44 Hook Failure Sept 2005 R44 Hook Cracking

Evidence of OverloadingEvidence of Overloading

ZK-HSF UH-1 on Spraying operations, accident

investigation revealed Tension Torsion strap failed

due previous main rotor overspeed.

ZK-HWP R22 Main Rotor Blade failed in Fatigue at

700hrs TSN, Nill corrosion. Repeated operation

beyond rated limit.

ZK-HWP Near TaumaranuiZK-HWP Near Taumaranui

Failed Blade RootFailed Blade Root

Fracture SurfaceFracture Surface

Fatigue Origin From Bolt HoleFatigue Origin From Bolt Hole

Fatigue OriginFatigue Origin

R22 Spray Tank DesignR22 Spray Tank Design

Empty Weight 880 lbs Pilot 170 lbs 30 min Fuel 23 lbs Spray Gear 90lbs

MAUW 1370 lbs

Available payload 207 lbs (max)Volume of Water 94 litres

Excess CapacityExcess Capacity

Available payload 94 Litres

Typical Tank Capacity 200 litres (100/side)

Survey of 17 R22 operators; 3 OK, 11 overloaded, 3 wouldn’t say

Proposed Approval Policy for Proposed Approval Policy for Agricultural Spray Systems.Agricultural Spray Systems. The tank capacity is not to exceed 105%

of the volume of water that could be carried within MAUW and C of G limits for the aircraft in condition ready for flight with fuel reserves meeting CAR 91.305 and crew onboard.

CAA Design Notices CAA Design Notices

Possible means of promulgating CAA Policy

ACU to issue as required As proposed by DDHs