Page 15 - Volume 12 Number 12

substantial improvement in the leak rate. Just use a huffer, not a Hoover®.
Do’s and Don’ts
Do check cabin leak rate and your flow packs. To test flow packs (on the ground or in the air) operate them one at a time while observing the Cabin VSI. Start with both packs going. To test the left side, turn the right pack off and watch the climb rate – it should go up briefly as the left pack adjusts to the change of flow, then it should come back down. Repeat on the other side. If the cabin VSI goes up to 500 ft/min that pack is getting weak; 1,000 ft/min indicates a dead pack.
Do check your leak rate too. An excessive cabin leak rate can throw off the results of your flow pack test. Inflow versus outflow – there are two sides to the equation and both must be examined.
Don’t ignore a weak flow pack just because you can make max differential on both packs. A strong flow pack can, and should, handle the load by itself.
Do send the pneumostat with the flow pack whenever repairing or exchanging.
Don’t assume that a pressurization problem is caused by the pressurization controller or the outflow valve.
Many pilots point to these before testing their flow packs or checking their cabin leak rate. Yes, controllers and valves can fail, but in a King Air the packs and/or leaks are the primary suspects when pressurization presents a problem.
It’s easy to take pressurization for granted as it doesn’t present a glaring red flag very often. But the system does degrade over time and it merits attention and proper maintenance. Keep an eye on it.
I confess I get great satisfaction from seeing older King Airs with many thousands of hours on the airframe still performing well. I had the great honor of speaking at the King Air Gathering III at Fredericksburg, Texas, in September. Thirty-plus King Airs clustered on the ramp was a stirring sight to see. Chatting and comparing notes with the owners and operators was an even greater pleasure. I hope everyone enjoys the heck out of their King Air. KA
Dean Benedict is a certi ed A&P, AI with over 40 years’ experience in King Air maintenance. He’s the founder and former owner of Honest Air Inc., a “King Air maintenance boutique” (with some Dukes and Barons on the side). In his new venture, BeechMedic LLC, Dean consults with King Air owners and operators on all things King Air related: maintenance, troubleshooting, pre-buys, etc. He can be reached at dr.dean@beechmedic.com or (702) 773-1800.
DECEMBER 2018
KING AIR MAGAZINE • 13