Spray Tank Mod Approvals

1
Spray Tank Mod Approvals

• Design Delegation Holders Seminar Oct 2005
• by
• Jack Stanton Team Leader Continuing
  Airworthiness Civil Aviation Authority

2
Recent 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

3
Evidence 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.

4
ZK-HWP Near Taumaranui
5
Failed Blade Root
6
Fracture Surface
7
Fatigue Origin From Bolt Hole
8
Fatigue Origin
9
R22 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

10
Excess Capacity

• Available payload 94 Litres
• Typical Tank Capacity 200 litres (100/side)
• Survey of 17 R22 operators
• 3 OK, 11 overloaded, 3 wouldnt say

11
Proposed Approval Policy for 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.

12
CAA Design Notices

• Possible means of promulgating CAA Policy
• ACU to issue as required
• As proposed by DDHs