Fortunately, one of the most serious vulnerabilities of piston-engine aircraft frequently proclaims its imminence on the instrument panel, giving the pilot a chance to cope safely.
In a long-ago interview with an export pilot—they are the sturdy souls who deliver small airplanes across cold oceans to buyers waiting overseas—I asked him what he thinks about on those tediously long flight legs in cockpits cramped to the point of discomfort by specially installed long-range fuel tanks.
“Heading, and oil pressure,” he answered.
Even if the only water you overfly in your trainer is a small lake that served as a checkpoint on your last cross-country, a top-notch takeaway from his response is that a low oil-pressure indication requires immediate investigation—and if it is accompanied by high oil temperature, “there is good reason to suspect an engine failure is imminent,” as the pilot operating handbook for a Cessna 182S Skylane cautions. For that airplane, the POH says that a pilot observing low oil pressure should “reduce engine power immediately and select a suitable forced landing field. Use only the minimum power required to reach the desired touchdown spot.”
In discussing abnormal engine-instrument indications, the Airplane Flying Handbook lists several causes of low or fluctuating oil pressure indications (see Figure 17-11). In each instance, it advises the pilot to land as soon as possible.
Ignoring or discounting low-oil pressure indications—the Cessna 182S displays it in two places: on a gauge, and as an annunciation—invites trouble. According to the NTSB, a factor involved in a fatal October 2006 accident involving a Piper PA–32R-300 single-engine airplane on a cross-country flight that experienced “oil starvation” in Dry Prong, Louisiana, was a flight instructor’s “improper in-flight decision in delaying to seek an emergency landing site following a loss of oil pressure indication.”
The report notes that “while in cruise flight, the low oil pressure warning light flickered, and the oil pressure dropped,” but the instructor decided to continue.
“About 20 minutes later, the engine made a ‘slight clatter noise’ and the instructor elected to divert to a closer airport”—but it was too late.
“Shortly thereafter, there was a loud ‘bang’ and the engine seized,” the report said, describing evidence of the engine’s “internal catastrophic failure consistent with a lack of sufficient lubrication.”