![\"Flow](\"https:\/\/www.newsbeep.com\/us-ny\/wp-content\/uploads\/2026\/09\/Screenshot-2026-08-31-at-3.50.53-PM-e1788217377977.jpg\")
<\/p>\nThink about that headline before going shopping for a used airplane. The image below is a so-called Flow Pack (there\u2019s one per PT-6A engine) used on the Cessna 425 Conquest I. High-tech by 1980s standards, this pressure-regulating and shut-off valve is a major component in the aircraft\u2019s pressurization system. Hot engine bleed air (around 500\u00b0 F and 100 psi) pumps through it before flowing into the cabin to serve various functions, including providing pressurization outflow, feeding deice boots, and powering pressure-driven flight instruments. This Flow Pack is an airworthiness-critical item for good reason \u2026 the Cessna\u2019s maintenance manual describes it as a firewall shut-off valve, essentially turning the bleed air off in case of a fire indication. There is also a pressure regulator that reduces bleed air pressure, plus a cabin bleed air shut-off valve. With no overhaul or exchange support, it\u2019s an orphaned component that essentially grounds an otherwise capable Conquest I should the part fail. This third-party support gotcha is one that every used airplane buyer should consider before spending big on an aging bird. And when it comes to support, fleet size probably matters.<\/p>\n
Support Gone By<\/p>\n
It\u2019s a one-of-a-kind Flow Pack that\u2019s used on the Cessna 425 and I\u2019m told there was only one source for approved overhauls and it wasn\u2019t Textron Aviation, which partly supports legacy Cessna models. The Flow Pack used on the Conquest I (the aircraft originally entered service around 1981 and ran through 1984) was originally designed and manufactured for Cessna by Consolidated Controls, which made plenty of other components and was eventually purchased by Eaton Corporation. With seemingly little interest in the Flow Pack for the Conquest I (the Conquest II followed, but that model uses a completely different system), Eaton entered into a support agreement with aerospace OEM Ontic Engineering & Manufacturing. Ontic went on to become the sole provider of service, overhauls, and parts support for the Conquest I\u2019s Flow Pack for years. Owners said Ontic did a decent job of supporting the Conquest\u2019s Flow Packs, cycling them into and back out of the field without issue, and providing the ability to purchase replacement parts (diaphragms, solenoid valves, etc.) through approved vendors just as Eaton did. All was fine, if not expensive, until it wasn\u2019t.<\/p>\n
I talked at length with AvBrief reader Scott Dickey, who owns a Conquest I that sits at the top of the fleet\u2019s foodchain. He sank eye-watering amounts of money into improving his aircraft (and his skills to fly it right) with new avionics, nice paint work, a modern interior, plus all the right maintenance and training. All that, only to have this Flow Pack extinction issue hang over the airplane because the sole support facility decided to pull the plug on its support.<\/p>\n
Despite its short production run and small fleet size, Cessna\u2019s entry-level turbine twin works for owner-flown missions, especially when the plan includes eventually moving into a Cessna light jet as Cessna\u2019s marketing hoped for. For Conquest I owners like Dickey, the aircraft indeed proves to be a good owner-flown business machine, and he relies on it to haul employees for regional travel and other company needs. Sadly, the big investment is jeopardized when a single critical assembly goes extinct because the only remaining support facility pulls the plug.<\/p>\n
<\/p>\n
If you are wondering, as I was, the most common failure of the Flow Pack is that it does not turn off; it is essentially designed to fail in the \u201con\u201d position so there is no disruption of pressurized air. It\u2019s a must-have component\u2014yes, different from the ones used on other PT6A-powered models including King Airs, Cheyennes, and even the model 441 Conquest II. Certainly, anyone contemplating the purchase of a Conquest I should pay close attention to the maintenance history and current status of each installed Flow Pack. Typical prices for the 425 range from around $850,000 to well north of $1 million. <\/p>\n
The reality check for the rest of us, which could apply to any aging machine: It\u2019s speculation, but maybe there is not enough demand for Ontic to keep supporting the Flow Packs. The Conquest I fleet size is small\u2014roughly 180 airplanes in service. And after savvy Conquest I owners hoarded and shelved Flow Packs, the rotable supply is depleted. Dickey said some of these good units have sold for $45,000. Attempts at finding another vendor have failed\u2014except for one last idea.<\/p>\n
Funding Development for a Replacement<\/p>\n
So what do you do for a near-million-dollar turboprop that could be grounded indefinitely at any time should an extinct Flow Pack fail? Spend a lot of money by finding someone to build and certify it. Dickey started from scratch and set out to find other manufacturers that might have the capability to pull off the production of a replacement unit. None of the companies he approached were interested. He eventually came upon one that manufactures aircraft control valves and air conditioning components, plus mission-specific major aerospace items. Since it is early in the project, the company wishes not to be named. That identity is unimportant, but the process for fabricating and earning FAA approval for a component like a Flow Pack is critical.<\/p>\n
Perhaps the easiest way to do it is by duplicating the design of the original Flow Pack (perhaps changing a few things here and there to increase reliability) and setting out for FAA Supplemental Type Certificate (STC) approval as a drop-in replacement for the original. The STC should apply to Conquest 425 models with PT-6A-112 and -135 engines. The benefit of pursuing an STC is that it gives the manufacturer and STC holder more flexibility (over a Parts Manufacturer Approval, or PMA) to make design changes to the component for improvements. It also curtails flight testing, though there will be some testing at the tail end in a designated Conquest to prove the new Flow Pack works as designed.<\/p>\n
\u201cThe biggest deal with this is we\u2019ll be able to buy brand-new Flow Packs with indefinite support,\u201d Dickey said. But there is an expensive catch: It is up to aircraft owners to put up six figures upfront in fixed-fee, nonrecurring engineering (NRE) costs. The next step is rallying Conquest I owners to throw their money into the ring to fund the project through Conquest Fleet Programs LLC, which was specifically set up for the task by several Conquest owners. The organization is working out the details, but each participating investor could have access to the parts for a locked-in price.<\/p>\n
When Shopping<\/p>\n
Luckily, finding alternative parts for the majority of smaller aircraft is not as complicated as sourcing the Flow Pack in a Cessna Conquest, though it might not always be less expensive. Earning new FAA approval requires experience and deep pockets. Certainly, manufacturers that are part of current large private equity suppliers should step up and fill the gaps for orphaned parts\u2014and many do. Our job as smart aircraft owners is to think about long-term support before paying big for an aircraft from a small fleet.<\/p>\n","protected":false},"excerpt":{"rendered":"Think about that headline before going shopping for a used airplane. The image below is a so-called Flow…\n","protected":false},"author":2,"featured_media":347717,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[37],"tags":[9,24,63,122,124,123],"class_list":["post-347716","post","type-post","status-publish","format-standard","has-post-thumbnail","category-queens","tag-new-york","tag-new-york-city","tag-nyc","tag-queens","tag-queens-headlines","tag-queens-news"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us-ny\/wp-json\/wp\/v2\/posts\/347716","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us-ny\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us-ny\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ny\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ny\/wp-json\/wp\/v2\/comments?post=347716"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us-ny\/wp-json\/wp\/v2\/posts\/347716\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ny\/wp-json\/wp\/v2\/media\/347717"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us-ny\/wp-json\/wp\/v2\/media?parent=347716"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ny\/wp-json\/wp\/v2\/categories?post=347716"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ny\/wp-json\/wp\/v2\/tags?post=347716"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}